Question

Which of the following is a solution to 2cos x + 1 = 0?

A.
60°

B.
120°

C.
210°

D.
300°

Answer 1

B. 120

Explanation:

2cos x + 1 = 0

2 cos x = -1

cos x = -1/2

x = cos^1(-1/2)

(cos inverse (-1/2))

x = 120°

Answer 2

the answer is b
2cos x + 1 = 0
2 cos x = -1
cos x = -1/2
x = cos^1(-1/2)
(cos inverse (-1/2))
x = 120°