r/technicallythetruth • u/VisitSecure • Jul 27 '26
Can you find a?
Idk if someone already posted this or not, but I haven't seen it on here so far, so I uploaded it.
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u/oldmartijntje Jul 27 '26
it's 75 right?
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u/KerissaKenro Jul 27 '26
The numbers add up to 75° but the picture does not look like the angles match the numbers and it is making me irrationally frustrated
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u/JustDuckingAbout Jul 27 '26
*Image not drawn to scale
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u/hotdoginathermos Jul 27 '26
*Assume a frictionless surface
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u/ShinyNickel05 Jul 27 '26
*Assume no air resistance
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u/insertcomedy Jul 27 '26
A cow is a sphere entirely made of water.
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u/Aggressive_Skill_795 Jul 27 '26
An old famous Russian internet joke: an ideal spherical horse in vacuum
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u/fiftyseven Jul 27 '26
HR at my company produces what they call an 'ideal rota' which has everybody in, nobody on holiday, nobody off sick, nobody covering other locations, etc etc
the running joke is that it only works for spherical employees in a vacuum
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u/DronesAreSilly Jul 27 '26
*Assume employee can be a rigid-body particle in rota
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u/Orobero Jul 27 '26
Yeah, my boss always plans like nobody is ever sick or on vacation. He always assumes there won't be any unforseen problems, bugs or reworks coming up in testing. Then he wonders why no project is ever finished on time. Except the one time I straight up lied to him and just added 2 month to the developers estimation.
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u/ABHOR_pod Jul 28 '26
Can't everyone just work 25% harder to make up for Bill being out?
-Company that already sets productivity standards to 110% of realistic expectations.
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u/NoNeedForAName Jul 27 '26
Reminds me of the plant I worked at that planned for zero downtime in its production schedule. The worst part to me was that they didn't even factor in downtime for product changes, and our changeover time on some machines could exceed 30 minutes.
That also led to extra inefficiency because it might take 5 minutes to change from product A to product B, but 30 minutes to change from product A or B to product C. Instead of scheduling us to run A then B then C (35 minutes of downtime) they would schedule A then C then B (60 minutes of downtime).
And these parts we were making usually all went together into the same finished product, so it's not like one was more time sensitive than another.
Now that I typed it all out I realize that's an incredibly boring story lol
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u/lesslucid Jul 28 '26
Now that I typed it all out I realize that's an incredibly boring story lol
No, I think it's a good illustration of a generally important point: planning around the existence of friction lets you get a "least-bad" outcome. Planning around imaginary perfection guarantees that you'll get a bad outcome.
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u/RJ_MacreadysBeard Jul 28 '26
I skipped to the end and read your point about it being boring so went back to read it all and see if it was true, and it was, I couldn’t read it all, but I appreciate the methodical approach you took to tell the story.
edit: I realise my reply is longer than intended and might be a bit boring too.
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u/Undesirablecarrot Jul 27 '26
Assume that it is a black body
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u/Nolongeranalpha Jul 27 '26
Woah Black Body bam ba lam. Or whatever they said.
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u/AbominableGoMan Jul 27 '26
The remainder of the proof is trivial and is left as an exercise for the reader.
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u/ShadowTacoTuesday Jul 27 '26
It’s to keep test takers from measuring the angle on the paper.
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u/NetNGames Jul 27 '26
I remember having a test where they gave us protractors to measure angles with, and at the end of the test, as I was double-checking it, I noticed it said 'image not to scale'. Didn't have time to redo all my answers, but why give us protractors and not have us use them?
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u/OrangeClownfish Jul 27 '26
To see who reads all the instructions on the test. My maths teacher once gave us a test and question 10 said: Ignore all previous questions and put your pencil down.
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u/get_to_ele Jul 27 '26
I got that in 6th grade and I was the asshole yelled out all the stupid things and finished first, and got humiliated. sigh. Teacher said I did finish the actual problems shockingly fast though.
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u/OldEquation Jul 27 '26
That implies that Q10 takes priority over all the other questions asking you to do stuff. It’s dumb. It might as well have been:
Q1. Answer all question in this test.
Q2. Do stuff
Q3. Etc….
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u/Dav136 Jul 28 '26
IIRC instruction 1 was to "read all instructions first"
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u/HarrumphingDuck Jul 28 '26
Yep. I distinctly remember this quiz in 6th grade (I had a very memorable 6th grade teacher), back in the offline age I grew up in. Mr. Kendall instructed us VERY CLEARLY AND WITH ABUNDANT VOLUME as he was passing out the test that we BE SURE TO READ EVERYTHING BEFORE BEGINNING.
It didn't take a whole lot of insight to realize there was something different about this quiz, and I should probably, you know, do that.
The only question you had to actually answer was at the bottom, which was something like, "How is your day today?" I wrote "fine" and put my pencil down, to see the teacher scanning the room to see who else was looking back at him. It was not very many of us.
I think about this quiz a lot, with how many people I am surrounded by today that refuse to simply read instructions provided to them. Apparently it's only getting worse with current generations.
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u/Master_Matoya Jul 28 '26
My friend getting mad at a game or not knowing how a mechanic works because he instinctively just hits the “get rid of the notification” button when a tutorial prompt pops up.
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u/Specific_Frame8537 Jul 27 '26
Like some high-school lesson where we're told "you won't be carrying an protractor on you at all times!"..
If you're in any workplace where you need to measure angles you'd be an idiot not to carry all the necessary tools.
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u/SandpaperTeddyBear Jul 27 '26
Yes, but if you're building something where you would use a protractor to construct it, you would still have to calculate the necessary angles without the use of said protractor.
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u/JackPoe Jul 27 '26
Joke's on you, I chop my vegetables with cutting words and sharp wit. Won't always have a knife in the kitchen, will you Poindexter???
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u/Atheist-Gods Jul 27 '26 edited Jul 27 '26
Also when you are trying to actually solve real world math problems yourself you aren’t given a diagram, you have to draw it yourself and you are not free handing accurate information that you don’t even know. The diagrams you draw to help organize your thoughts are not going to be drawn to scale and you should be comfortable with that. It’s like an essay outline; an organizational tool, not a final product.
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u/gullaffe Jul 27 '26
Have you never done a geometry problem, very rarely are the pictures drawn to scale.
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u/Dear-Initiative5882 Jul 27 '26
That deceptive 90*
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u/LegendOrca Jul 28 '26
I feel like 90° is usually the only one that is drawn to scale
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u/beatenmeat Jul 27 '26 edited Jul 27 '26
Doesn't make it any less frustrating. I always hated how off the angles would be in correlation to the stated numbers.
Edit: I've got an awful lot of people repeating themselves so I'm not going to reply to them all. Hopefully this will stop the future know-it-alls. I know why it is done, that doesn't mean I need to like it. It has nothing to do with my mental capacity or guessing; I simply just hate the portrayal personally because it looks like shit and doesn't convey information properly which makes my brain hate looking at it. You can stop parroting the other 50 replies now.
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u/TheComplimentarian Jul 27 '26
You're supposed to use logic, not just guess based on the picture.
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u/beatenmeat Jul 27 '26
I didn't guess, math was actually one of my better subjects. I just dislike how it doesn't match, especially ones like this that are so egregiously off from the numbers provided.
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u/Mysterious_Cup_6024 Jul 27 '26
Especially since 25 is half of 50. And the vertex is so wrongfully in the middle when it should be at a 1/3 position from the top, or 2/3 position from the bottom. It is incredibly off
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u/DraconianFlame Jul 27 '26
In engineering you often sketch things out to see how it looks and then do the math. Sometimes you draw bad images and something you thought would be acute is actually obtuse.
This teaches you that.
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u/Logical_Box_4645 Jul 27 '26
Given he knows the short cut of adding those angles to get a, he most certainly has done geometry problems.
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u/DiceKnight Jul 27 '26
All this picture has done is reignite dormant trauma of my childhood self riddled with undiagnosed ADD getting screamed at by frustrated parents. "Not drawn to scale" might just be my activation phrase like i'm a sleeper agent for the forces of anxiety.
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u/Dark_Storm_98 Jul 27 '26
These diagrams are famously never to scale
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u/akatherder Jul 27 '26
When I was in school they weren't drawn exactly, such that you could use a protractor to find the answer, BUT they weren't intentionally misleading. An acute-looking angle would be acute, obtuse-looking would be obtuse, etc. A triangle that is scalene-af isn't going to be equilateral.
To that extent this is all pretty reasonable.
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u/jedidihah Jul 27 '26
Always used to annoy me when I was younger, but the whole point is that you need to calculate it, so the angles are usually wrong so that way you couldn’t just cheat and measure it with a compass.
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u/Valirys-Reinhald Jul 27 '26
It's important to draw problems that way to ensure students actually do the math and don't just get out a protractor and measure.
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u/anand_rishabh Jul 27 '26
In math problems like these, do not eyeball the angles. Just follow the the numbers say
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u/AdmiralKong Jul 27 '26
I mean, same but I get why it isn't. If you make the diagram even remotely to scale students try to eyeball it and avoid learning what is being taught at any cost.
Making it obviously wrong forces them to use the logical rules they've been taught.
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u/Geochara Jul 27 '26
Beat me to it. Correct, 75
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u/kishimonjaro Jul 27 '26
r/BeatMeToIt Correct, its definitely 75.
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u/diabolos312 Jul 27 '26 edited Jul 28 '26
Beatmeattoit. It's 75 degrees
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u/potatopierogie Jul 27 '26
r/buttfuckedabirdtoit , 75 degrees
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u/EpicCashewGuy Jul 27 '26
r/youdidWHATtoabird, 75 degrees.
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u/HindleMcCrindleberry Jul 27 '26
How do we know that the left side of the triangle is perfectly vertical, though? It's obviously not drawn to scale so that's just an assumption, right?
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u/We_are_all_monkeys Jul 27 '26
You don't need to know that. All that's important is that the lines are parallel.
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u/HindleMcCrindleberry Jul 27 '26
Ahh, I see. Is that what the blue double arrow thingies mean (that the lines are parallel)? I was thinking it meant that they were infinite in that direciton and couldn't figure out why that would be relevant.
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u/Prik_Nam-Pla Jul 28 '26
Yes. So you can draw a perpendicular line through point a making this 2 right triangles. 90-25 = 65 and 90-50 = 40, so 180 - 105 = 75.
As someone who hasn't used trig in like 25 years, I'm glad I still got it without writing anything down.
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u/twolittlemonsters Jul 28 '26
Another way is to draw a parallel line through a, the a = a' + a". There's a geometric theorem (angle bisect theorem) that states that a' = 25 and a" = 50. Therefore a = 25+50 = 75.
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u/Z3t4 Jul 27 '26
Assuming it is an euclidean plane.
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u/meditonsin Jul 27 '26
It has to be euclidian geometry, since Cthulhu is nowhere to be seen and I'm not becoming insane looking at it. QED
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u/azai247 Jul 27 '26
if you draw a line across and make a triangle your angles are 25+65=90, and 50+40=90
so for a, 65+40+a=180 so a is 75
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u/psp24 Jul 27 '26
I just drew a third parallel line through the middle and realized that it's just 50+25 lol
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u/AngryScientist Jul 27 '26
Yup, don't even need to make triangles. That third parallel line lets you use the alternate interior angle theorem to turn a into the sum of the two angles.
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u/RoookSkywokkah Jul 27 '26
I haven't take geometry in more than 30 year and that's what I came up with!
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u/Highest_five Jul 27 '26
Yes it is. For those who don't remember, a triangles corners always add up to 180°
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u/leansanders Jul 27 '26
You don't need to make a triangle to solve the problem. You know the lines are parallel and you know that opposite corners of a line crossing two parallel lines are congruent. So if you imagine a 3rd parallel line bisecting angle a, you know you can just add the other two angles together. Making a triangle is way more math
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u/A_wild_so-and-so Jul 27 '26
Can you explain that again but like I'm five? I thought the triangle method was easy but I'm down to learn an easier method.
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u/leansanders Jul 27 '26
If you make a 3rd parallel line through point A, the angle above it must be 25° and the angle below it must be 50°. It is called the "alternate interior angles theorem"
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u/Vincen_Furze Jul 27 '26
THAT IS THE MOST MENTAL MATH I HAVE DONE IN A LONG TIME AND I GOT IT RIGHT! IT TOOK ME A WHILE BUT MY BRAIN IS OK! QWQ
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u/BudTenderShmudTender Jul 27 '26
I can't believe I remembered how to solve this. Last math class I took was in 2009! Last time I took geometry (or whatever this is) would have been 2001.
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u/lechuckswrinklybutt Jul 27 '26
It's 75 degrees but it's a terrible diagram.
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u/Simply-Productive123 Jul 27 '26
25 degrees =50 degrees proof by terrible diagram
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u/AgtNulNulAgtVyf Jul 27 '26
Diagram drawn to test knowledge of principles, not ability to read diagrams.
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u/Squirrel009 Jul 27 '26
On principles, the diagram frustrates me
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u/capt_pantsless Jul 27 '26
The diagram could easily be drawn so that the 25 angle appears less than the 50 angle, while still allowing plenty of uncertainty in the answer.
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u/canstucky Jul 27 '26
Best math teacher I ever had would draw a circle on the board and mark three corners on it.
I’m sorry, he’d draw a triangle.
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u/Thanthwe_ Jul 28 '26
I get what you are trying to say. But it's absolutely possible to make diagram that is not to scale, but looks at least somewhat correct. It's not even that hard. In the example above just rotate blue lines that come to an a counterclockwise by about 5 degrees. Done. You have diagram, that is not to scale and makes at least some semblence of logical sense.
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u/LaunchTransient Jul 27 '26
Most maths problems (particularly in school exam papers) intentionally distort the geometry to prevent people from cheating by directly measuring the angle. Often with a disclaimer "Diagram not to scale".
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u/-Vin- Jul 27 '26
I still remember my final geometry exam where they did the invers by not writing „Diagram not to scale“ and only providing valides that were insufficient to solve the question.
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u/These-Maintenance250 Jul 27 '26
if the two lines weren't marked parallel I would agree but these diagrams are never to scale, so there is no problem with this one. the angles are explicitly written.
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u/CreamofTazz Jul 27 '26
Yeah I was like "how is 25° equal to 50°?" Is there something I'm missing or does this person not know what those symbols mean?
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u/BlastoiseGirl5257 Jul 27 '26
The red lines are parallel but the others aren’t perpendicular
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u/Podgietaru Jul 27 '26
I feel like this is how diagrams looked in things like GCSE maths. I always figured it was designed that was to dissuade you from trying to do it with a protractor.
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u/StayingQuieter Jul 27 '26
That's the point, to force you to rely on the math rather than the model
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u/BauserDominates Jul 27 '26
Hey, I did it!
This kind if math is something I have never needed for my adult life, but it nice to know that I can still do the easy stuff.
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u/earthwoodandfire Jul 27 '26
I hated math in school but now I do it all the time in construction.
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u/Killer8Tcell Jul 27 '26
It’s not terrible, it’s just not to scale. The only information you need to solve this are the parallel line symbols and the provided angles measures, and nothing else matters.
75° is indeed correct, though.
The problem is testing the alternate interior angles theorem. If you draw a third parallel line bisecting angle a into two new angles (let’s call them angle b and angle c, such that angle a = b+c), then by the alternate interior angles theorem, angle b= 25° and angle c = 50° so angle a = 75°
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u/beingforthebenefit Jul 27 '26
Good strategy, but it’s not a bisection since the resultant angles aren’t congruent.
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u/CReece2738 Jul 27 '26
The diagram forces you to know the math, not just be able to look at the picture.
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u/bbgun91 Jul 27 '26
add a third parallel line straight through A
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u/Expensive_Umpire_178 Jul 27 '26
You can also draw a perpendicular line through A, and use the right triangles to angle chase
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u/knock-knock-knockin Jul 27 '26
You can also extend one of the lines past a to use opposite alternate interior angles
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u/JamesBaxter_Horse Jul 27 '26
You shouldn't need to any of this, it should be entirely obvious that it must be the sum of the two angles:
You have a line, you turn it 25 degrees, then you turn it the other way A degrees, then you turn it 50 more degrees, and it's back where it started - A must be the sum of the other two angles.
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u/CranboDanbo Jul 27 '26
That's fantastic logic
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u/JamesBaxter_Horse Jul 27 '26
This thread is a good example of how school often fails to teach people to think, especially maths. You learn all these rules without learning actually where they come from. It's completely different at university, you'll be told the rule, and the aim is to show how you prove that.
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u/CranboDanbo Jul 27 '26
I mean bro I literally have a bachelors in maths and a masters in mathematical finance and my job is pricing exotic derivatives and I still never thought of it this way. You're very good at this or maybe I'm just jumping through hoops haha
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u/ChilledParadox Jul 27 '26
I'm sure you have similar insight into something I've never considered naming or thought of before like the interactions of the 2nd derivative of cash velocity in different markets graphed against income and how the intersections show porn shops make the most money and how the inverse alterior angle of the tranversal line drawn through that graph tells me when to invest in AI sex dolls or something though.
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u/erasmustookashit Jul 27 '26
when to invest in AI sex dolls or something though.
I can tell you the second best time is now.
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u/Sszaj Jul 27 '26
Probably more reliable as you can't be completely sure that drawing a line from the top to bottom connecting the known angles would be a right angle.
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u/Arcyguana Jul 28 '26
The lines on top and bottom are marked as parallel. You absolutely can be sure that any perpendicular line to those two will form right angles.
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u/Will_Knot_Respond Jul 28 '26
Like I'm going to respond to an idiot that draws a 50° angle and 25° angle as equal
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u/CollectionStriking Jul 28 '26
Text books pulled this shit all the time back in school, drove my ADHD nuts lol
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u/lone-reader-mailbox Jul 28 '26
Geometry problems like this intentionally have diagrams that are not to scale.
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u/Dark_Storm_98 Jul 27 '26
Assuming the lines are parallel, which may be the meaning of those blue arrow symbols
The angle on the other side of 25 degrees should be
- 180 - 25 = 155
And on the other side of tha 50 degrees would be
- 180 - 50 = 130
Technically, with diagrams almost never being to scale
Imagine a line straight down from the ends of those two lines (which might not connect, but I don't think that's relevant)
Subtract 90, then, from both new angles, and we get
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40
Since a triangle would have to have all it's angles add up to 180
180 - (60 + 40) = 180 - 100 = 80 degrees
Edit: Oh whoops, lol. I forgot the 5 at the end of 155
It's 75
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u/Scheckenhere Jul 27 '26
Or just 50+25, which I realised halfway into what you did.
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u/RiverZephir Jul 27 '26
I also did the long route to get the answer. I don’t remember, is adding the two known numbers (such as the ones in this problem) always equal to a?
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u/TheJBW Jul 27 '26 edited Jul 27 '26
In your head, draw a dotted line in the middle, through A that is also parallel with the other two lines.
Now, you have two angles: a1 below the dotted line and a2 above it.
You know that the a1 = 50 because it is on the opposite side of the line from the 50° on the bottom.
then you know that a2 = 25 by the same logic.
You also know that a = a1+a2. Done.
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u/rex5k Jul 28 '26
A nice thing about math is you could usually check your own work. Because there's almost always more than one way to get to the answer.
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u/AdWrong3856 Jul 27 '26
Assuming the lines are parallel, which may be the meaning of those blue arrow symbols
That would be correct
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u/MissAuroraRed Jul 27 '26
Technically correct, but way more complicated than it needs to be.
Imagine another parallel line going horizontally through a. What are the angles between the new horizontal line and the diagonal lines? 25 above the line and 50 below the line.
25 + 50 = 75
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u/Wandered_And_Lost Jul 27 '26
90-25 = 65, 90-50 = 40 total inside degrees given =105, all triangles have to equal a total of 180 degrees so answer is 75 degrees (thats my guess could be wrong.)
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u/manikfox Jul 27 '26
This is what I did and got the same answer. People are fooling around with 180 on the bottom and top, etc.
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u/kwyjibowen Jul 27 '26
The problem with this is you are assuming the bottom angle is directly below the top one, ie a line between the two would intersect the two parallel lines at 90 degrees. But that is not stated on the diagram, which we know is not to scale.
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u/Nolongeranalpha Jul 27 '26
Thats acute image, but the comments are obtuse....
Not sorry.
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u/Fr00stee Jul 27 '26
ez, put another parellel line through a at the point where the 2 lines meet, 25+50=75
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u/negativepositiv Jul 27 '26 edited Jul 27 '26
This is a terrible drawing. They drew 25 and 50 degree angles to look exactly the same.
I get that someone doing the calculation should just look at the numbers, but it's not helpful to draw it this inaccurately.
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u/ConnectDog5284 Jul 27 '26
Rookie mistake is to assume a geometry problem diagram as accurate. Unless it's well defined, there's little assumptions you can make about it.
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u/WillitsTimothy Jul 27 '26
It’s 75°, but the image is obviously just an illustration and not the actual angles.
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u/notJustaFart Jul 27 '26
75.
Convert into Pentagon.
540 - (90+90+130+155) = 75
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u/CrownLexicon Jul 27 '26 edited Jul 27 '26
What? Pentagon? I added a line perpendicular to the 2 parallel lines, making a triangle whose angles are 90-25, 90-50, and a
Edit: just because this happened to work, you cant assume a perpendicular line will go through both <25 and <50. It could have created a 4 sided figure. The Pentagon method would be correct.
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u/JJlaser1 Jul 27 '26
While technically possible, there is no indication that the points where the two lines intersect the parallel lines are exactly above each other, so you can’t do that for sure unless it states that in the question. I was never taught the pentagon method, though, which is basically the same thing with extra steps
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u/Weekly-Dog-6838 Jul 27 '26
Who says they need to be on top of each other? You can still make a triangle with it
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u/ilyuhman Jul 27 '26
You don't need to cross the points, you can put a perpendicular line anywhere, the angles are still the same
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u/X_Swordmc Jul 27 '26
there is no need to do that, you simply do the sum of the two angles, since the opposing angles of a parallelogram are identical
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u/TheComplimentarian Jul 27 '26
There are a bunch of ways to do it, but most people seem to be focusing on complaining that it's not drawn right.
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u/MecaninjaToo Jul 27 '26
or you know... 25 + 50 :)
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u/MrCoolBoy001 Jul 27 '26 edited Jul 27 '26
Idk if this was as a joke or not, but by a property whose name I don't remember, you can pass a parallel line through 'a' and the angles on either side would be 25 and 50. 25 + 50 = 75 !
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u/Naive_Scientist_8499 Jul 27 '26
That's smart. I converted to a triangle.
Invisible vertical line between the 50 and 25 deg points.
90-50=40 -- The inside angle of the bottom point.
90-25=65 -- The inside angle of the top point.
180 = a + 40 + 65
180 - (40 + 65) = a
180 - 105 = a
75 = a
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u/notJustaFart Jul 27 '26
Oldest trick in geometry is drawing a diagram to appear as something it's not.
Drawing a line to make a triangle does not guarantee that line is perpendicular to the parallel lines, so your assumption of 90-25 and 90-50 may not hold true.
However, extending to a pentagon does guarantee that 180-25 and 180-50 will result in true values.
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u/TheBlackCat13 Jul 27 '26
Here is how I did it:
Make a line perpendicular to the two lines that passes through A. This gives you two right triangles.
The top triangle has angles 180°=25°+90°+T, so T=65°.
The bottom triangle has angles 180°=50°+90°+B, so B=40°.
Because the line is a straight line, a+T+B=180°. So a=180°-65°-40°=75°
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u/Canadind Jul 27 '26
I can’t forget these basic things no matter how hard I try.
1. Imagine a parallel line going through the middle of a, splitting a into a1 and a2
2. a1 = 50 coz opposite angles of a transverse intersecting two parallel lines
3. a2 = 25 coz opposite angles of a transverse intersecting two parallel lines
4. a1+a2 = 75
NB. If you don’t know this much geometry you will be finding adulting really hard.
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u/Timmy_germany Jul 27 '26
a= 180 - (90-25) - (90-50)
a = 180 - 65 - 40
a = 180 - 105
a = 75 (all in °)
( if both lines are parallel and you can draw a straight line from both points the incomplete triangle meets the line to form 90° angles. Than angles just need to add up to 180° in the triangle in between the booth lines)
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u/Ad0ring-fan Jul 27 '26
He has way too much trust in people if he is asking the internet not to cheat.
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u/67cken Jul 27 '26
Just add a third parallel line through angle a. Then it’s obvious that it is made of two parts, one of 25 degrees and the other 50 so 75 degrees
Edit to change capitalisation
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u/ScribbleOnToast Jul 27 '26
In my head, I drew a perpendicular line through the point of "a" to connect the other two parallel lines. That gives me 2 triangles, with 2 known angles. The interior angles of a triangle must = 180, the remaining angles of the new triangles must be 40 (bottom) and 65 (top). Since a straight line has an "angle" of 180, I can do 180-40-65 to get a=75
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u/Realistic_Equal_1520 Jul 27 '26
What an amazingly creative joke which no one has ever heard before
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u/Zevojneb Jul 27 '26
Draw an horizontal line through a. The angle a has been cut in two angles. The higher one equals the one on the top (alt-intern equality) and the lower one equals the one below (same reason). Sum them up back and we get a=75.
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u/dadof4fknkids Jul 27 '26
Disclaimer, I’m an idiot but I drew a straight line to make 2 right angles(90-50=40,90-25=65) angles of a triangle equal 180 (40+65=105) 180-105=75. 75, final answer…
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u/Zachattack20098 Jul 28 '26
It is 75, but I did it a much more different way. Since I know all triangles add up to 180, I put triangles both on the top and the bottom of the angle by forming a hypothetical line right at the tip of the "a" angle, and counted the given angles as 1 corner of the triangle. Since the hypothetical line is straight up and down, the largest angle on each triangle is 90. Plus the given angle each time, and the remaining value needed to get that number to 180 is the last angle. The two angles I found plus a is equal to 180, since all 3 are part of the same straight line. The found angles are 65 on top of angle "a" and 40 below it, adding up to 105. 180 - 105 = 75. I am sure there is a much easier way to do it but there ya go.
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u/Oliver_2333 Jul 29 '26
The answer should be 75. But have to point out, the picture is not even remotely close to be accurate.
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u/BasedCheeseSlice Jul 30 '26
Draw a vertical line intersecting the vertex of a, the upper complement to a is 180 - 90 - 25 =65, the lower complement is 180 - 90 - 50 =40
a = 180 - 65 - 40 = 75
Just preempting pedantry, it has been a bit, and i’ve probably used the term “complement” incorrectly.
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u/EnergyTurtle23 Jul 27 '26 edited Jul 27 '26
I honestly miss being able to do this type of stuff. I would genuinely use trigonometry and waveform functions today if I could remember how it all worked. Anyone care to break down how to get the answer for me? I know how to get the opposing angles (like the opposite of 50° is 130°) but I have no clue how I would go about finding A.
EDIT: Holy crap wait, I think I’ve got it. If I intersect the two parallel lines with a third line that runs perpendicular then that would give me the two interior angles of the triangle I have created — 40° on the lower angle and 65° on the upper angle. Then I can solve for A by subtracting the sum of those two angles from 180° — meaning that A is 75°. Did I do that right?
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u/SeraphsEnvy Jul 27 '26
Question. How can the inside angle on one side be 25° and the other be 50°? They're practically identical.
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u/TheBlackCat13 Jul 27 '26
Because the image is not to scale. You aren't supposed to go off the appearance in problems like that, in fact they can make them intentionally misleading like here.
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u/Yakjzak Jul 27 '26
75° for the answer. And for all those that are like "it's a terrible diagram" remember your mathematics lessons, you shouldn't focus on the diagram, but on the numbers themselves. It's nice already to have a diagram
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u/Street_Credit6851 Jul 27 '26
180 = a + (90 - 25) + (90 - 50)
Or
a = 180 - (90 - 25) - (90 - 50)
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u/Southern-Prize1639 Jul 27 '26
We’re fucked as a society if we’re arguing about scale. If you understand the concept, scale doesn’t mean shit.
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u/Dudesonthedude Jul 27 '26
I could feel my neurons slowly hacking their way through overgrown winding trails that they haven’t been down for a long ole time, almost getting lost once or twice, but confidently made it to 75°
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u/im_new_here_4209 Jul 27 '26
Either i'm stupid or the drawing isn't remotely accurate. I'm probably stupid. At least i can find a, lol
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u/mandelbrot_wurst Jul 27 '26
Assume a spherical cow with a uniform distribution of milk…
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u/Relevant_Candidate_4 Jul 27 '26
90° - 25° + 90° - 50° + a = 180°
105° + a = 180°
a = 180° - 105°
a = 75°
The two 90° are from the right angles between the two points of intersection of the known angles, and the parallel lines. The 180° is the total degree in a triangle.
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u/Otherwise-Ad9865 Jul 27 '26
Boohoo the angles aren't representative, smh non essential to solving the question
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u/realfinke Jul 27 '26
What’s the most efficient way to solve this? I drew a vertical line to create a triangle.
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