63. Witch of Agnesi Let y (x+ 4) = 8 (see figure). dy a. Use implicit differentiation to find d x b. Find equations of all lines tangent to the curve y (x + 4) = 8 when y = 1. dy c. Solve the equation y (x + 4) = 8 for y to find an explicit expression for y and then calculate d x d. Verify that the results of parts (a) and (c) are consistent. y A y(x2 + 4) = 8 X