6. Find the slope of the tangent to the curve y = sin 2x - cos 2x at x = a. 0 C. 4 b. 1 d. -2 7. Find the equation of the tangent to y = cos 2x at the point 4 a. y= -2x C. y = -2x + 7 b. y = 2x+ 1 d. y=-x+1