sin^2x+cos^2x=1sin(A+B) = sinAcosB+cosAsinB sin(A-B) = sinAcosB-cosAsinB 
cos(A+B) = cosAcosB-sinAsinB tan(A+B) = (tanA+tanB)/(1-tanAtanB)tan(A-B) = (tanA-tanB)/(1+tanAtanB)