Question

In triangle ABC, a = 4, b = 6 and cosC= -1/4, what is the length of side c?

Answer 1

A

Explanation:

c^2 = a^2 + b^2 - 2ab cos(C)

c^2 = 4^2 + 6^2 - 2(4)(6)(-1/4)

c^2 = 16 + 36 + 12

c^2 = 64

c = √64

c = 8