Question

In triangle ABC, a=7, b=3 and cos C = 1/2. The value of c is

1. Sqrt 8
2. Sqrt 37
3. Sqrt 27
4. 4

Answer 1

Correct option: 2 -> sqrt(37)

Explanation:

To solve this problem, we just need to use the law of cosines. This law is used to find the third side of a triangle, when we have the two other sides and the angle between them.

The equation of the law of cosines is:

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

So, we have that:

c^2 = 7^2 + 3^2 - 2 * 7 * 3 * (1/2)

c^2 = 49 + 9 - 21

c^2 = 37

c = sqrt(37)

Correct option: 2