Question

Need help with precalcuclus will give owl bucks!!

Answer 1

whats the question

Answer 2

ok what do u need help with

Answer 3

I will post 1 by 1. Ill show .

Answer 4

ok sounds good

Answer 5

both of u can help

Answer 6

But, actually if you can can you please post it in another question not the same tab

Answer 7

Y

Answer 8

so that way when you give you medals we get the full credit

Answer 9

Its only fair

Answer 10

Ok lets do this question first

Answer 11

ok

Answer 12

Im giving owl bucks not really medals

Answer 13

Thanks tho

Answer 14

ok

Answer 15

so first a triangle equals 180 all together when added up

Answer 16

Yes

Answer 17

And im pretty sure c is a right angle

Answer 18

so that equals 90

Answer 19

You can use the law of cosines here. You can't make any assumption about the angles not labeled as having a specific value.

Answer 20

everything is not drawn to scale we can propose

Answer 21

u remember
\[\cos A = \frac{ b^2 + c^2 - a^2 }{ 2bc }\]
???????the cosine rule

Answer 22

Ohh ok so its not drawn accurately?

Answer 23

I honestly dont know anything but the wordp re caluclus in pre caluclus lol. I would love to have teacher explanation or any explanation is fine

Answer 24

@sydneymmelin yes, you can't conclude that it is a right angle just because it looks sort of like it might a right angle. If it isn't labeled as such, either 90 degrees or with little square, you have to assume that it is not.

Answer 25

but yes i guess since we are looking for side A it would be

Answer 26

wait would we just use pythroean therom?

Answer 27

nah u cant use pythagorean theorem ..its not a right triangle

Answer 28

No, Pythagorean Theorem only works on right triangles, and this is not a right triangle.

Answer 29

Oh i see, thanks

Answer 30

So how should i go about this

Answer 31

@matlee
http://www.askiitians.com/iit-jee-properties-and-solutions-of-triangles/solution-of-triangles/

Answer 32

But, don''t we have to find the other angles

Answer 33

@sydneymmelin we simply need to apply the cosine rule

Answer 34

I think we do. But we can say angle C is 90 cus it can be any number within 1-158

Answer 35

Ok cosine rules

Answer 36

What is the cosine rule and how should i know when to use it

Answer 37

well really you cant just assume the angles cause it would be inaccurate

Answer 38

sorry i meant cant*

Answer 39

oh lol right

Answer 40

To solve a triangle is to find the lengths of each of its sides and all its angles. The sine rule is used when we are given either a) two angles and one side, or b) two sides and a non-included angle. The cosine rule is used when we are given either a) three sides or b) two sides and the included angle.

Answer 41

@matlee

Answer 42

Oh thats great lol

Answer 43

We need to find the length of side \(a\). We have angle \(A\), and sides \(b\) and \(c\).

\[\cos A = \frac{-a^2+b^2+c^2}{2bc}\]

Answer 44

We need to rearrange that to get \(a\) alone on one side. Can you do that algebra?

Answer 45

Kind of

Answer 46

Ok i see why is cos cus the two side adjacnet and hypotenus

Answer 47

@matlee why are u considering it to be hypotenuse.....Its NOT a right triangle

Answer 48

oh i thought the largest one was the hypotenus

Answer 49

In a right triangle, the long side is the hypotenuse, but a non-right triangle does not have a hypotenuse.

Answer 50

cosA(2bc)-b2 - c2 = -a2 i dont know how to get a alone after that

Answer 51

how about you multiply both sides by -1, and then take the square root?

Answer 52

u got the value of b,c and A
use calculator to get the value of cosA

Answer 53

(square root(-1(cosA(2bc)-b2 - c2) = (square root ) a)

Answer 54

cos of 22 i do?

Answer 55

\[\cos A = \frac{-a^2+b^2+c^2}{2bc}\]\[2 b c \cos A = -a^2+b^2+c^2\]
\[2bc \cos A - b^2-c^2 = -a^2\]
\[-2bc\cos A + b^2 + c^2 = a^2\]\[a = \sqrt{b^2+c^2-2bc\cos A}\]
Take the positive square root.

Answer 56

Thank you how do you d it so fast lol that takes me for ever

Answer 57

Ok so now we have that

Answer 58

\[\cos(22^\circ) \approx 0.927184\]

Answer 59

Ok

Answer 60

\[a\approx \sqrt{(17)^2 + (36)^2 -2(17)(36)(0.927184)} = 21.2\]