(d) I = √2xy ds_where c is defined by the parametric equations x = 4 cos 0, y = 4 sin 0 between 0 = 0 and 0 = П 3'

Need to find the Horizontal and Vertical Tangent Line of r=3-2 cos theta. I know I need to set the each equation to zero but I am having difficulty breaking down the trig functions. For dy: 2 sin^2 theta+4 cos theta = 0 for dx : 2 sin theta cos theta-4 sin theta = 0

how would i evaluate the definte intergral

Find dx where w cos z - cos 4x cos 4y + sin 4x sin 4y and z= 4x + 4y.