$60\degree$  

 $-60\degree$  

 $150\degree$  

 $-150\degree$  

 $f\left(x\right)=\cos\left(x\right)$  

 $f\left(x\right)=\sin\left(x+90\degree\right)$  

 $f\left(x\right)=\sin\left(x\right)$  

 $f\left(x\right)=\sin\left(x-90\degree\right)$