Cosine of difference between 2 Angles
Returns the cosine of difference between 2 angles.
NOTE: cos (a) - cos (b) = 2*sin ((b + a) / 2)*sin ((b - a) / 2)
Returns the cosine of difference between 2 angles.
NOTE: cos (a) - cos (b) = 2*sin ((b + a) / 2)*sin ((b - a) / 2)