Question

Given a triangle with a = 16, A = 39 degrees, and B = 28 degrees, what is the length of c? Round to the nearest tenth.

Answer 1

Firstly, solve for the value of angle C by using the concept that the sum of the three angles of a triangle should be 180 degrees. 
                       C = 180 - (A + B) = 180 - (39 + 28) = 113 degrees
After which, use the concept of sine law which state that the ratio of sine of the angle to the side opposite to it should be equal,
                       (sin A / a) = (sin C / c)    ;    (sin 39 / 16) = (sin 113 / c)
Solving for c gives an answer of c = 23.40.