prove that, (cos(3x) - cos (7x)) / (sin(7x) + sin(3x)) = tan(2x)
prove that, cos(3x) = 4cos^3(x) - 3cos(x)
tan(x) = sin(x)/cos(x) must come into the first one
The Attempt at a Solution
tried seperating the fraction so there is only one cos term on top, but I don't know how to deal with the sin terms on the bottom.
I haven't got a clue for the second one