I am trying to do the problem below but I don't understand how to do it. Can you please show me how to do it? DON'T give me the answer, explain to me how to get the answer. http://img134.imageshack.us/img134/9168/untitled1au7.jpg [Broken] Point C moves at a constant rate along semicircle centered at ) from A to B. The radius of the semicircle is 10 cm, and it takes 30 sec for C to move from A to C. Angle COB has measure y radians, angle OCA has measure z radians, and AC = x cm as indicated in the figure. a) What is the rate of change, in radians per sec, of x with respect to time? b) What is the rate of change, in radians per sec, of y with respect to time? c) x and y are related by the Law of Cosines; that is, y^2 = 10^2 + 10^2 - 2(10)(10)cos y. What is the rate of change of x with respect to time when y = π/2 radians? d) Let D be the area of ΔOAC. Show that D is largest when x = π/2 radians.