Question

just want to know if I did this problem right.

In triangle ABC, a = 9, c = 5, and B = 120°. Find b2

I got 128.5

Answer 1

@jagr2713

Answer 2

well if you are using the cosine rule its

\[b^2 = 9^2 + 5^2 - 2 \times 5 \times 9 \times \cos(120)\]

Answer 3

so I think your answer is incorrect...

\[2 \times 5 \times 9 \times \cos(120) = -45\]

so the problem is really

\[b^2 = 9^2 + 5^2 - (-45)\]

Answer 4

so 151 @campbell_st ??

Answer 5

that's what I got

Answer 6

okay, can you help me with another one please? @campbell_st

Answer 7

sorry, I'm about to go to class.