What is the derrivative (dy/dx) of the equation 2 = cos 4x - cos 2y in terms of x and y?

A common C4 question where the student would need to use implicit differentiation to obtain an equation with the derrivative in it. 0 = -4sin4x + 2(dy/dx)sin2y. Then all that is required is rearranging the expression to make dy/dx the subject. (4sin4x) / (2sin2y) = (2sin2x) / sin2y = dy/dx