Problem 3. Let C be the curve defined by the equation ray + 3 +y2 -0. Find all points (a, b) on C' such that line tangent to C at (a, b) is horizontal. Problem 4. Let y = f(x) be a function that is implicitly defined by the equation sin(y?) = (2r - sin(I))y?. 1. Find a formula for f'(x) in terms of r and f(x). 2. Does f(x) have any local extrema