(cos^2x-sin^2x)-sin4x+sin^22x=0

x=22.5

Step-by-step explanation:

(there's a correction in the question since the I did this one before, so I know)

(cos²x-sin²x)²-sin4x+sin²2x=0

or, cos²2x-sin4x+sin²2x=0

or, 1-sin4x=0

or, sin4x=1

or, 4x=90

or, x=22.5

step-by-step explanation:

just plug in each number for x and see which ones work and don't

a is the right answer