0Sum/difference identities:
sin (x + y) = sin(x) cos(y) + cos(x)
sin(y),
cos(x + y) = cos(x) cos(y) - sin(x)
sin(y),
sin(x - y) = sin(x) cos(y) - cos(x) sin
(y),
cos(x - y) = cos(x) cos(y) + sin(x)
sin(y),
Double angle identities:
sin(2x) = 2 sin(x) cos(x),
cos(2x) = cos2(x) - sin2(x),
cos(2x) = 2 cos2(x) - 1,
cos(2x) = 1 - 2 sin2(x),
tan(2x) = [2 tan(x)]/[1-tan2(x)],
