Convert the rectangular equation to an

Question

equation in (a) cylindrical coordinates and (b)
spherical coordinates.
4(x^2 + y^2) = z^2

Answer 1

This is just a pair of cones:
z^2 = 4r^2

If θ is the angle from the z-axis, then the cone is just

since z=2r,
tanθ = 1/2