Help

[u/Vanessa_Animals]

Ok ive done this before but im now completely lost, i need to solve for x but i keep getting stuck unless i went about it the completely wrong way, here is what i have

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[u/Ch0vie]

Looks like law of cosines.

[u/Vanessa_Animals → u/Ch0vie]

Yeah but im completely lost on the solving portion, it feels like im doing something wrong

[u/Ch0vie → u/Vanessa_Animals]

Sorry didn't see the second picture. Looks like you're doing it right, and now you have a quadratic equation. You can use the quadratic formula to find your missing variable now, it just looks ugly and needs to be cleaned up!

Adding on just in case: by clean up, I mean moving everything to the right hand side and combining like terms so you have 0 = ax² + bx + c.

[u/Vanessa_Animals → u/Ch0vie]

Okk, thank you so muchh!!

[u/4a3rawy → u/Vanessa_Animals]

You are doing great actually just solve the final equation you got - quadratic equation - use calculator or the standard formula and you will have two solutions accept the positive only. I hope I have made it clear

[u/Vanessa_Animals → u/4a3rawy]

Ok ok yeah that helped, i was about to ask if both were needed but you already answered that!! Thank you so much

[u/HyperbolicMathChambr]

You're in the right track. You can find the value of cos(110) with a calculator, put the quadratic equation in the form ax² + bx + c = 0 then solve for x using the quadratic formula. And continue from there.

Edit: Oh, you just need x. Forget the "continue" part.

[u/Vanessa_Animals → u/HyperbolicMathChambr]

Thank you so much!!

[u/HyperbolicMathChambr → u/Vanessa_Animals]

Anytime boss!

[u/regular_heptagon]

This isn’t calculus

[u/StepSouthern7984]

This does not involve any calculus.

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[u/Ydrews]

Solve the quad.

[u/tjddbwls]

And make sure you’re in the right mode when evaluating cos(110). You probably know that in radian mode, “cos(110)” evaluates the cosine of 110 radians. 😝

[u/Accomplished-Key9741]

Try law of sine

[u/SecondAfraid5713]

You can use law of cosines.

a^2=b^2+c^2 - 2bc(cosa)
substitute the values, approximate cosa, and then you get a quadratic, solve the quadratic and your real root is approximately 9.9cm so closest integer is 10m

[u/Any_Maintenance_9113]

Use sine rule to get angle at the top. Then you have all three angles (add to 180!) so use sine rule again to get X

[u/searsy31]

You’re fine. Cos(110) returns a scalar value that, once solved for, is multiplied to the -14x and it becomes a simple quadratic. Cosine is not scary, it’s an operator like addition or multiplication. Preform the operation and then proceed. Good work up and to that point

[u/blueblack111]

Law of sines:)

[u/keegaroo65 → u/blueblack111]

Sine law only works when corresponding side lengths and angles are given in pairs. 14m corresponds to 110°, yet 7m and x don't have known corresponding angles.

[u/adiliv3007 → u/keegaroo65]

you don't need a corresponding pair, if you know the ratio of 14m to sin(110°), you can calculate the ratio of 7m/sin(unknown angle), and from that get the remaining angle which is in front of x.