sin(x+y)
sinx cosy + cosx siny
sin(x-y)
sinx cosy - cosx siny
cos(x+y)
cosx cosy - sinx siny
cos(x-y)
cosx cosy + sinx siny
tan(x+y)
tanx +tany / 1-tanx tany
tan(x-y)
tanx +tany / 1+ tanx tany
sin2x
2sinxcosx
cos2x
cos^2x -sin^2x
cos2x
1-2sin^2x
cos2x
2cos^2x-1
tan2x
2tanx / 1-tan^2x
sin^2u
1-cos2u / 2
cos^2u
1+cos2u / 2
tan^2u
1-cos2u / 1+cos2u