根据倍角公式cos2x=1-2(sinx)^2=2(cosx)^2-1((sinx)^2)^2=(1-cos2x)^2/4=1/4+[(cos2x)^2]/4-1/2cos2x=1/4+(1+cos4x)/8-1/2cos2x=3/8+1/8cos4x-1/2cos2x对上式求不定积分,得3x/8+1/32sin4x-1/4sin2x+C即3x/8+1/32sin4...