1) Cos 30°= √3/2            
  *Look at unit circle
  *Find 30°
  *Cos is the X value
  *The X value is √3/2    

 2) Sin 60°= √3/2
  *Look at unit circle
  *Find 60°
  *Sin is the Y value
  *The Y value is √3/2

3) Cos 2π/3=look at answer page under "more"