∫ (sin2x)/(sin²x) dx
= ∫ (2sinxcosx)/(sin²x) dx
= 2∫ cosx/sinx dx
= 2∫ (1/sinx) d(sinx)
= 2ln|sinx| + C
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∫ sin³xcos²x dx
= ∫ sin²xcos²x d(-cosx)
= -∫ (1 - cos²x)cos²x d(cosx)
= ∫ (cos⁴x - cos²x) d(cosx)
= (1/5)cos⁵x - (1/3)cos³x + C