Question 195626
sinx = cos2x
sin(x) = 1-2sin^2(x)
2sin^2 + sin - 1 = 0
(2sin - 1)(sin + 1) = 0
sin = 1/2, sin = -1
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x = pi/6, 5pi/6 (from 1/2)
x = 3pi/2 (sin = -1)