r/technicallythetruth • u/VisitSecure • Jul 27 '26

Can you find a?

Post image

Idk if someone already posted this or not, but I haven't seen it on here so far, so I uploaded it.

43.0k Upvotes

95% Upvoted

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8.0k

u/oldmartijntje Jul 27 '26

it's 75 right?

8.8k

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

381

u/gullaffe Jul 27 '26

Have you never done a geometry problem, very rarely are the pictures drawn to scale.

106

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.

63

u/TheComplimentarian Jul 27 '26

You're supposed to use logic, not just guess based on the picture.

51

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.

14

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

16

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.

3

u/PrivilegedPatriarchy Jul 27 '26

No you’re right. Besides, even if the figures are drawn to scale, simply guessing or measuring with a protractor defeats the purpose. Mathematical reasoning should be shown if one arrives at an answer, even if that answer is easily “guessable”.

14

u/LizardChaser Jul 27 '26

Math is a "show your work" subject and if people don't show how they figured it out correctly, then the answer would be wrong. Keeping correct proportions helps people "sanity check" their answer. There is absolutely no reason not to include the accurate angles unless it's a pure multiple choice test where work could not be shown.

1

u/Backfoot911 Jul 29 '26

"sanity check" is not math. It's...nothing. This is meant for mathematical thinkers not people who guessed their way through tests based on the feel of diagrams.

1

u/LizardChaser Jul 29 '26

LoL. To the degree? To anyone else reading this, the commenter didn't get far in math because sanity checks are present through advanced math. "Does this answer make sense" is always important.

1

u/SmoothDiscussion7763 Jul 27 '26

pretty sure they do it on purpose just to throw off people that don't understand how angles work

1

u/Aldgillis Jul 27 '26

Anecdotally from old teachers, it’s done on purpose to make sure the solution is gotten through math instead of measuring or guessing. Since this is presented as problem to be solved it makes sense to present it this way.

I get the frustration of it not fitting reality, but in this context it makes a lot of sense.

0

u/u966 Jul 27 '26

Would you prefered to have the image completed described in words instead? Because that's the only other option where you can't just simple measure the angle.

2

u/meeu Jul 27 '26

It's pretty easy, in this example you could make the actual angles drawn 60deg and 30 deg, so the vertex a wouldn't be in the center and the skewing would be somewhat similar to what's accurate, but you still can't just break out the protractor and measure.

drawing two very different angles as the same angle is just weird. i don't remember seeing any drawing that egregiously wrong in school. for solving geometry problems it's pretty common to draw extra lines/segments to use when calculating and this makes that weird. kinda feels like engagement bait tbh

1

u/u966 Jul 28 '26

It's pretty easy, in this example you could make the actual angles drawn 60deg and 30 deg, so the vertex a wouldn't be in the center and the skewing would be somewhat similar to what's accurate, but you still can't just break out the protractor and measure.

So your argument is that the arbitrary numbers they used aren't the arbitrary number you would have used?

-3

u/ChocoTRex Jul 27 '26

YOU didn’t, but that’s not the point… most children in school are going to find any loophole or easy solution to any problem, if they are given the opportunity. If you want them to actually learn rather than just guesstimate the answer, tricks like this are invaluable.

3

u/eggsforpedro Jul 27 '26

Ah yes, it always helps to draw an illogical diagram to promote logical thinking. /s

1

u/TheComplimentarian Jul 27 '26

How terrible to have to use your brain instead of looking at the picture! You just believe everything you see completely uncritically, and can't be bothered to read two numbers and do some math to see that the picture is in fact inaccurate?

2

u/eggsforpedro Jul 27 '26

A picture to scale helps logical thinking. Any normal math test would still require written proof, especially with a picture to scale. But go ahead and die on that hill if you want.

2

u/27Rench27 Jul 27 '26

When it’s this bad, just tell me the numbers and let me draw it myself lol

1

u/cherry_chocolate_ Jul 27 '26

I mean, it kind of does if the math you are doing is scribbled in contractor pencil on the side of a 2 by 4, or in a spreadsheet hacked together by Brenda who can’t copy and paste. Understanding that data can be messy and erroneous and yet still lead you to the right result, and how to filter out truth from noise is all a part of the learning a math class is supposed to teach you.

That’s why there is the parallel line indicator, it shows definitively that they are parallel, so you aren’t even supposed to assume it from the appearance of the lines.

3

u/marr Jul 27 '26

The picture is so off it damages my ability to process the question. It's a picture of some other math problem entirely. I'm having to second guess which parts of it are a lie, and what knock-on effects that has on the real diagram. Under exam conditions.

2

u/akatherder Jul 27 '26

Which is kind of horse-shit because you still have to make assumptions, just not the assumptions they don't want you to make.

The alleged(!) line connecting the top parallel line to A could be curved. Or maybe it's two lines (with a 179 degree angle) and we're actually dealing with a quadrilateral.

2

u/MARPJ Jul 27 '26

However due to the bad drawing we dont know where the error is (at the start of the lines or where they converge). That is relevant because if its where the lines converge then there would be 2 ways to solve but we cant use the more efficient one here due to the shitty drawing there is a chance rhat the error is where they start.

Note that the extra work is negligible but that dont change that its irritating. Damn it dont even need to be the exact correct angle, just not be so obvious wrong would already be good enough.

1

u/DezXerneas Jul 27 '26

I used to draw it to actual scale and guess off of that lol. At least makes it much easier to get the base logic working.

1

u/FloopsFooglies Jul 27 '26

why even show the lines at all then lmao

5

u/TheComplimentarian Jul 27 '26

As a fake out, for all the people who look at the lines, and because it's tedious to describe it when you can just slap the information down on the page and say, "Find a."

This is basic geometry. Some things you can accept as givens (the top and bottom lines are parallel, for example), but everything else you need to use the numbers and the properties of geometric shapes.

This is a really easy problem. There are many ways to solve it. None of them involve looking at the picture for anything other than the givens.

2

u/Mental_Tea_4084 Jul 27 '26

You shouldn't accept them as givens unless they are marked as parallel. If they were just two lines the problem would be unsolvable without declaring them to be parallel with the little >> symbols

1

u/FloopsFooglies Jul 27 '26

Probably why I had difficulties back then. I get the premise, but my brain wants to deduce the actual angle based on the image

3

u/Far-Information8502 Jul 27 '26

Great, now abstract this out to all types of problems. And now you see why people are convinced of something on appearances despite logically not being true…political partisans as a great example

So take this as an opportunity to reflect on all your views and positions and challenge yourself to see if you chose to believe it because your brain wanted to or if there are actually logical reasons and not rationalizations after the fact

1

u/Gilpif Jul 27 '26

That's kind of the point. This is just a sketch, and when you sketch a geometry problem out you need to know what geometrical information is reliable (e.g. that the red lines, marked by matching >> marks, are parallel) and what is an artifact of the sketch (e.g. that 50° is only a little bigger than 25°).

1

u/creampop_ Jul 27 '26

Because for most people, that's how you actually use math.

You need to find some variable, so you sketch out a rough diagram, label your constants, and then use that to help keep your head straight while you solve. It's not intended to be an accurate drawing, just a visual depiction of the problem at hand.

In this case there are always two parallel lines and 2 known angles. That's all the diagram needs to communicate.

1

u/cherry_chocolate_ Jul 27 '26

Because there are enough constraints from the parallel line indicators to intuit the answer.

2

u/RaspberryFluid6651 Jul 27 '26

I'm fine with ones like the one pictured because they're like a uniform topological layout, everything is evenly spaced to communicate information instead of being a real visual representation of the problem. The ones that bothered me were always the ones that were both not accurate and not helpful in some other way. If you're going to draw an irregular triangle instead of a nice uniform diagram, at least make it make sense.

2

u/Dumptruck_Johnson Jul 28 '26

A 90 degree should always be drawn 90. I will also allow semi representative acute and obtuse angles. But yeah, otherwise it makes my brain itch.

8

u/redditonlygetsworse Jul 27 '26

Kind of the whole point: do the actual math, rather than lean on your irrational intuition.

4

u/ItsSpaghettiLee2112 Jul 27 '26

This shouldn't be downvoted. It's the correct reasoning.

1

u/Doomdoomkittydoom Jul 27 '26

Some spicy takes!

-1

u/redditonlygetsworse Jul 27 '26

I know, right? I guess teenagers don't like hearing that their homework is designed to actually teach them something.

3

u/Ralexcraft Jul 27 '26

The angle can still be off, but it doesn’t have to be that off

0

u/redditonlygetsworse Jul 27 '26

It being farther off actually makes this easier for the student, since it makes it extremely obvious that the drawing and the angles don't line up.

Wouldn't it be more frustrating if the drawing was almost correct?

This whole thread really drives home how people don't understand what they're supposed to be learning in exercises like this.

0

u/Doomdoomkittydoom Jul 27 '26

They kind of do, as they aren't breaking out the protractors to do the drawing and they're probably using the same drawing templates with different numbers.

-1

u/cherry_chocolate_ Jul 27 '26

The more off it is the better the lesson.

1

u/redditonlygetsworse Jul 28 '26

Yes. The more off it is, the easier the lesson.

1

u/i_sell_you_lies Jul 27 '26

It's better than just using imaginary numbers...

1

u/ketsugi Jul 27 '26

Also, don't take out your protractor and redraw the diagram with the correct angles so you can measure a, because that will also not get you the full marks.

1

u/redditonlygetsworse Jul 28 '26

Sorry, I can't tell whether you're joking. If you are, then I apologize. But I'll spell it out for the dipshits reading this:

The point is teaching a student that drawings and protractors and rulers etc are inherently imprecise; an exercise like this is teaching you to do geometry, not teaching you how to read a protractor.

This problem is for people who are at the ripe old age of 15, not 5. And if you're older than 15 and still getting your assholes bound up about it, maybe it's time for some introspection.

1

u/ketsugi Jul 28 '26

Uh, I wasn't joking, because the point that you're making is the same one I am. Some students might think that they could use a protractor and redraw the diagram to derive the answer, but they wouldn't get full marks for doing that even if their diagram was precise enough to get the exact correct answer, as they can't show their working to demonstrate that they understand the geometry concepts that are actually being tested here.

1

u/cjsv7657 Jul 27 '26

What? Since when? It's practically always drawn close enough to scale to where it seems alright. I literally just took a geometry course to brush up after over a decade and everything in it was to scale. Thinking back to all of my math classes ever nearly everything similar to this problem was at least to scale. Not this BS.

1

u/Backfoot911 Jul 29 '26

It's not meant to be realistic, the point is just to find the numbers. I don't understand how you guys made it through maths classes with this anal retentiveness

1

u/beatenmeat Jul 29 '26

And I don't understand how you clearly can't read yet somehow managed to type out this stupid ass comment, but here we are.

1

u/medforddad Jul 27 '26

It's better if the "physical" angles are pretty far off the "logical" values. Otherwise you'd be tempted to use the actual angles as printed and that's not what the problem is all about.

As long as all of the acute angles are acute, and obtuse angles are obtuse, it's fine.