I need help to prove identity sin(x+2pi)=sinx

We'll have to use the following formula in order to prove
the given expression:

sin (a+b) = sin a*cos b + sin b*cos
a

Let a = x and b = 2`pi`

sin
(x+ 2`pi` ) = sin x*cos 2`pi` + sin 2`pi` *cos x

But sin
2`pi` = 0 and cos 2`pi` = 1

sin (x+2`pi` ) = sin x*1 +
0*cos x

sin (x + 2`pi` ) = sin
x

Therefore, the given identity sin (x+2`pi`
) = sin x is verified.