SOLUTION: sin4x-2sin2x-1=0

Question 799273: sin4x-2sin2x-1=0
Answer by lwsshak3(11628) (Show Source): You can put this solution on YOUR website!
solve for x
sin^4x-2sin^2x-1=0
let u=sin^2x
u^2=sin^4x
u^2-2u-1=0
solve for u with quadratic formula:

a=1. b=-2, c=-1
ans:
u≈-0.4142(reject)
or
u≈2.4142
..
sin^2x=2.4142
x=�√2.4142≈�1.5537(radians)
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