3. Consider the following curve: ( 202 + y? ) 2 = 202 + You can assume throughout this problem that this curve is differentiable at every point other than (0, 0). Ignore the point (0, 0) for this question. Prove that there are exactly 6 points on the curve with horizontal tangent lines. Find the coordinates of these points. (Hint: Think of y as a function of x, and use implicit differentiation. You should find that 4 of the points lie on a common circle of the form x2 + 2 = 72)