Question

In triangle ABC, a = 4, b = 6, and cos C = − 1/4. What is the length of side c?

Answer 1

The length of side c would be 8.

Step-by-step explanation:

Given that,

a = 4

b = 6

cosC = -1/4

If we are given two sides and angle, the law of Cosines can be used to find the third side:

$c^{2} = a^{2} + b^{2} - 2ab (cos(c))$

By inserting the values in the formula, we get

$c^{2} = 4^{2} + 6^{2} - 2.4.6 (-\frac{1}{4} )$

$c^{2} = 16 + 36 + 12$

$c^{2} = 64$

$\sqrt{c^{2} } = \sqrt{64}$

c = 8.

Therefore, the length of side c would be 8.