2sinx –1 = 0

cos 2x = 1 + sin 2x 1 – 2sin2x = 1 + 2sin x.cos x. 2sin2x + 2sin x. cos x = 0. 2sin x (sin x + cos x) = 0 so sin x = 0 or tan x = –1 etc. sin x.cos12º – cos x.sin12º = sin(x – 12º) = etc. 3cos 2x – sin 2x – 1 = 0 3(cos2x – sin2x) – 2sin x.cos x – (cos2x + sin2x) = 0. 3cos2x – 3sin2x – 2sin x.cos x – cos2x – sin2x ... ................
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