Help with identities math problem?

[shocklightnin]

The question asks you to simplify sin(3pi/2+x).

I know that you've got to use the sin(a+b)=sinacosb+cosasinb

but I'm not sure how to solve it when it's not a special triangle.

Any help is much appreciated.

 

[shocklightnin]

Nevermind, figured out my silly mistake.