\(cos(\pi+x)=-cosx\)
\(sin(\pi+x)=-sinx\)
.
\(cos(\pi-x)=-cosx\)
\(sin(\pi-x)=sinx\)
\(cos \left(\frac{\pi}{2}-x\right)=sinx\)
\(sin \left(\frac{\pi}{2}-x\right)=cosx\)
\(cos \left( \frac{\pi}{2}+x \right)=-sinx\)
\(sin\left( \frac{\pi}{2}+x \right)=cosx\)