∫ sin 2x sin 4x sin 6x dx

We need to simplify the given equation to make it easier to solve


We know 2sinAsinB = cos(A – B) – cos(A + B)


sin4xsin2x =


The above equation becomes




We know 2sinAcosB = sin(A + B) + sin(A – B)


sin6xcos2x =


Also 2sinx.cosx = sin2x


sin6xcos6x =


The above equation simplifies to




We know




(where c is some arbitrary constant)


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