Question

How do you solve `4 cos^2 (2x + pi) = 3`?

Answer 1

Solve 4cos^2 (2x + pi) = 3

Ans: -75 and -105 deg

Explanation:

`4cos^2 (2x + pi) = 3`
`cos^2 (2x + pi) = 3/4 = 0.75`
`cos (2x + pi) = +- 0.866`
`2x + 180 = +- 30` deg

a. 2x + 180 = 30 --> 2x = 30 - 180 = - 150 --> `x = -75` deg
b. 2x + 180 = - 30 --> 2x = -30 - 180 = -210 # deg -> -> #x = - 105# deg