Im using the double angles, half angles:
sin^2x + cos ^2x = 1
sin(a+/-b)= sinAcosB +/- cosAsinB
cos(a+/b)= cosAcosB -/+ sinAsinB
tan(a+/-b)= tanA+/-tanB / 1-/+ tanAtanB
sin2A = 2sinAcosA
cos2A= cos^2A - sin^2A
cos2A= 1 - 2sin^2A
tan2A= 2tanA / 1 - tan^2A
sin A/2 = √1/(1-cosA)
cosA/2=...