Posted by **Daisy** on Tuesday, December 4, 2012 at 5:11pm.

Find all real solution of the equation sin^2x = -2+2cosx

- Math -
**Steve**, Tuesday, December 4, 2012 at 6:50pm
since sin^2 = 1-cos^2,

1-cos^2 = -2 + 2cos

cos^2 + 2cos - 3 = 0

(cos+3)(cos-1) = 0

cos=1, so x = 0,2pi,4pi,...

why not -3?

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