怎么求sin2x的导数
方法如下，
请作参考：
∫(sinx)^2(cosx)^4dx = (1/8)∫(1-cos2x)(1+cos2x)^2dx
= (1/8)∫[1+cos2x-(cos2x)^2-(cos2x)^3]dx
= (1/8)∫[1/2+cos2x-(1/2)cos4x]dx - (1/16)∫[1-(sin2x)^2]dsin2x
= (1/16)[x+sin2x-(1/4)sin4x]-(1/16)sin2x + (1/48)(sin2x)^3 + C
= (1/16)x - (1/64)sin4x + (1/48)(sin2x)^3 + C
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