Substitute `2x=z` in the given function
Also ` (d)/(dx)(2x)=(dz)/(dx)`
or `2=(dz)/(dx)`
`:. (dx)=(dz)/(2)`
and ` int sin 2x dx = int sin z ((dz)/(2))`
` =(1)/(2) int sin z dz`
` =(1)/(2)(-cos z)+c`
Substitute back for z , we get
`int sin 2x dx =(1)/(2)(-cos 2x)+c`