sin3x =? – InterviewSolution

1.

sin3x =?

Answer»

sin 3x = sin(x + 2x)sin(x + 2x) = sinxcos2x + cosxsin2x

Subtituting the values of sin2x and cos2x we get

sin 3x = (sinx)(1−2sin^2x) +(cosx)(2sinxcosx)

sin 3x = 3sinx−4sin^2 3x

sin3x = 3sinx-4sin^3x

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