Question

How do you use the law of cosines if you are given three sides 9, 6, 14?

Answer 1

Solve triangle knowing the 3 sides.

Explanation:

Use trig identity: c^2 = a^2 + b^2 - 2abcos C. Find angles A, B, and C

196 = 81 + 36 - 108cos C
108cos C = 117 - 196 = -79 ->`cos C = - 79/108 = - 0.73`
->`C = 137` deg
`sin B/b = sin C/c -> sin B = (bsin C)/c = (6(0.68))/14 = 0.29`
-->`B = 16.94`

`A = 180 - B - C = 180 - 137 - 16.94 = 26.06`