Question

In triangle ABC, a = 3, b = 5, and c = 7. Find the approximate value of angle A.
a. 22°
b. 38°
c. 142°
d. 158°

Answer 1

@amoodarya can you help please?

Answer 2

use law of cosine

Answer 3

i dont remember how to do that

Answer 4

\[b^2+c^2-a^2=2bc \cos(A)\]
put a,c,b in formula
you will find cos(A)

Answer 5

5^2+7^2-3^2=70cos a

Answer 6

A=22