okay time for math formulas:

Product Formula
2sinAcosB = sin(A+B) + sin(A-B)
2cosAsinB = sin(A+B) - sin(A-B)
2cosAcosB = cos(A+B) + cos(A-B)
2sinAsinB = -( cos(A+B) - cos(A-B) )

Factor Formula
sinx + siny = 2sin((x+y)/2)cos((x-y)/2)
sinx - siny = 2cos((x+y)/2)sin((x-y)/2)
cosx + cosy = 2cos((x+y)/2)cos((x-y)/2)
cosx - cosy = -2sin((x+y)/2)sin(x-y)/2)

Triple Angle Formula
cos3A = 4cos*3A - 3cosA
sin3A = 3sinA - 4sin*3A

Double Angle Formula
cos2A = cos*2A - sin*2A OR 2cos*2 - 1 OR 1 - sin*2A
sin2A = 2cosAsinA
tan2A = (2tanA)/(1-tan*2A)

R Formula
acosx + bsinx = Rcos(x-t)
acosx - bsinx = Rcos(x+t)
asinx + bcosx = Rsin(x+t)
asinx - bcosx = Rsin(x-t)