`intsin^20xcos^3xdx`

Explanation

`intsin^20xcos^3xdx`
=`intsin^20x.(1-sin^2x)cosxdx`
[Put sinx=t
Then cosxdx=dt]
=`intt^20(1-t^2)dt=int(t^20-t^22)dt`
=`1/21t^21-1/23t^23+C`
=`1/21sin^21x-1/23sin^23x+C`