Answer:
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
