Question

SOMEONE PLEASE HELP!

a = 4, b = 7, c = 10. What is the measure of angle A to the
nearest tenth?

Answer 1

17.2°

Explanations

To find angle A, use the cosine rule.

a^2 = b^2 + c^2 - 2 × a × c cos A

4^2 = 7^2 + 10^2 - 2 × 7 × 10 cos A

16 = 49+ 100 - 140 × cosA

16 = 149 - 140cosA

16- 149 = - 140cosA

-133 = - 140cosA

cosA = 133/140

cosA = 0.95

A = 17.2°