Answer:
What's the intervals for this question
Step-by-step explanation:
Answer:
x = 180
Step-by-step explanation:
First, you need to know
1. Double-angle formula:
cos(2x) = 
2. Pythagorean identity:

Back to your problem, replacing the variable by the above:

By Double-angle formula
By Pythagorean identity
Given 



, we know -1 < sinx < 1, for every x ∈ R



Answer:
Andre has the correct answer. When simplified his answer is equivalent to the original equation.