9. [-/1 Points] SCALCETS 14.6.035. ASK YOUR TEACHER Let fbe a function of two variables that has continuous partial derivatives and consider the points A(9, 2), 5(13, 2), C(9, 5), and D(14, 14). The directional derivative of fat A in the direction of the vector E is 7 and the directional derivative at A in the direction of AC is 4. Find the directional derivative of fat A in the direction of the vector AD. (Round your answer to two decimal places.) Need Help? _ Submit