Tutorial Exercise Two cars start moving from the same point. One travels south at 60 mi/h and the other travels west at 45 mi/h. At what rate (in mi/h) is the distance between the cars increasing three hours later? Step 1 Using the diagram of a right triangle given below, the relation between x, y, and z is z = x + y 2 V N x + y Step 2 We must find dz/dt. Differentiating both sides and simplifying gives us the following. 2z dy dt dz dx = 2x + 2y dt dt dz dt = 225 (x. dx + 16875 dy X dt X dt th NE