Question

How do you solve `f(x)=3-4cos2x`?

Answer 1

Solve f(x) = 3 - 4cos 2x

`x = +- 20.70` deg

Explanation:

3 - 4cos 2x = 0 --> cos 2x = 3/4 = 0.75
Calculator gives --> `2x = +- 41.41` deg
`x = +- 20.70 deg`
Check
x = 20.70 --> 2x = 41.41 -->cos 2x = 0.75
3 - 4(0.75) = 0 OK