Question

Find the angles

Diagram below,

I've found one angle on my own and need help finding the others.

Answer 1

So I got c= 10.98 DEG

Answer 2

How did you find that?

Answer 3

I used the formula

Answer 4

Uhm let me find it..
\[\frac{ \cos C = (a2 + b2 − c2) }{ 2ab }\]

Answer 5

Thos are suppose to be squared

Answer 6

Right - you used the cosine law. Why not just use it two more times for the other two angles?

Or better yet, use it once more, then subtract the two angles you have from 180 to find the third!

Answer 7

I just don't know the cosine law for the other two angles >.<

Answer 8

It's exactly the same! Don't get stuck on the fact that a, b, and c in your equation need to correspond exactly to a, b, and c in the figure. They're just three variables.

This time, set say you want to find angle a in your figure. Then a and b in your equation will be the two adjacent sides (in this case, sides b and c), and c in your equation will be the opposite side (in this case, side a).

Answer 9

Let me see...

Answer 10

hehe why did you leave the other post lol

Answer 11

Let me see...\[4^2+1.2^2-2(4)(1.2)Cos(B)\]

Answer 12

Is that right?

Answer 13

that equals to 3^2

Answer 14

how can solve without euqlity

Answer 15

\[\cos B=\frac{4^2+(1.2)^2-3^2}{2(4)(1.4)}\]

Answer 16

B=28.4579982553
repeat the same thing with other angle

Answer 17

don't use radians in calculator
otherwise you will always get wrong answers

Answer 18

Wait now I'm super confused

Answer 19

28.4579982553 can't be right

Answer 20

Because 3 is VERY close to 4

and I can't see 3 being the 2nd largest and far larger than 1.2 so how does it get such a small angle?

Answer 21

28.46 is correct!

Which makes the third angle what?

Answer 22

(PS. your drawing is not to scale so the angles won't necessarily match what you see in the picture)

Answer 23

But whattt that makes the third angle like 150 ._.

Answer 24

So? What's wrong with that?


^That's what your triangle really looks like!

Answer 25

for me makes perfect sense
the way you reasoning is off hehe
if you actually draw to scale you will see that the two angles are small
and one is huge
the diagram provided by @matt is good to illustrate this