Question

#1 Using the right triangle below, find the cosine of angle A.

Answer 1

Answer: 0.8

Step-by-step explanation:

Using the Cosine formula :

$Cos A = \frac{b^{2}+c^{2}-a^{2}}{2bc}$

$a = 6$

$b = 8$

$c = 10$

substituting into the formula , we have

$Cos A = \frac{8^{2}+10^{2}-6^{2}}{2(8)(10)}$

$Cos A = \frac{64+100-36}{160}$

$Cos A = \frac{164-36}{160}$

$Cos A = \frac{128}{160}$

Therefore :

Cosine of angle A = 0.8