Question

Show that sin (x + pi) = -sin x.

Answer 1

The answer in the procedure

Explanation:

we know that

`sin(A + B) = sin A cos B + cos A sin B`

In this problem we have

`sin(x + \pi)=sin (x)cos(\pi) + cos(x)sin(\pi)`

Remember that

`sin(\pi) = 0`

`cos(\pi) = -1`

substitute

`sin(x + \pi) = sin(x)(-1) + cos(x)(0)`

`sin(x + \pi) = -sin(x)`