Evaluate: `intsin^4x\ dx`

Explanation

`int sin^(4)xdx=int((1-cos2x)/(2))^(2)dx`
`=(1)/(4)int(1-2cos2x+cos^(2)2x)dx`
`=(1)/(4)int(1-2cos2x+(1+cos4x)/(2))dx`
`=(1)/(4)int((3)/(2)-2cos2x+(cos4x)/(2))dx`
`=(1)/(4)((3)/(2)x-sin2x+(sin4x)/(8)) +C`