1. The problem statement, all variables and given/known data Let C be the circle defined by (x-2)2+y2 = 1. If this circle is rotated along the y-axis, a torus will form. What is the Cartesian equation for the torus? 3. The attempt at a solution The solution manual says you just switch the x in (x-2)2+y2 = 1 with r=√(x2+z2) and simplify. Why would that work? Why does the x in the first equation equal the radius of the torus? I don't get it.