Question 46853
1.) (double angle)
cos(2x) = cos^2(x) - sin^2(x) = 1 - 2sin^2(x) = 2cos^2(x) - 1
2.) cos(a + b) = cos(a)sin(b) - sin(a)cos(b)
3.) (double angle)
sin(2x) = 2sin(x)cos(x)
4.) sin(a + b) = sin(a)sin(b) + cos(a)cos(b)