Trig Formulas
Half Angle
sin^2x=(1-cos2x)/(2)
cos^2x=(1+cos2x)/(2)
tan(x/2)=+-sqrt(1-cosx)/1+cosx)
Double Angle
sin(2x)=2sinxcosx
cos(2x)
cos^2x-sin^2x
2cos^2x-1
1-2sin^2x
tan(2x)=(2tanx)/(1-tan^2x)
difference
tan(A-B)=(sinAcosB-sinBcosA)/(cosAcosB+sinAsinB)
cos(A-B)=cosAcosB+sinAsinB
sin(A+B)=sinAcosB-cosBsinA
Sum
cos(A+B)=cosAcosB-sinAsinB
sin(A+B)=sinAcosB+cosAsinB
tan(A+B) =(sinAcosB+sinBcosA)/(cosAcosB+/sinAsinB)