Question

If you know that the value of a = 8, c = 12, and B = 72 degrees, how do you determine the values of A, C and b?

Answer 1

Trig identity: `b^2 = a^2 + c^2 - 2ac.cos B`

`b^2 = 64 + 144 - 192.(0.31) = 208 - 59.52 = 148.48` ->

`b = 12.18`

To find A, use the trig identity:`sin A/a = sin B/b`

`sin A = (a/b)sin B = (8(0.95))/12.18 = 0.62` -> A = 38.60 deg

C = 180 - A - B = 180 - 72 - 38.60 = 69.4 deg