A ladder 13 meters long rests on horizontal ground and leans against a vertical wall. The bottom of the ladder is pulled away from the wall at the rate of 0.6 m/sec. a) Find the rate at which the top of the ladder is sliding down the wall when the bottom of the ladder is 5 m from the wall. b) Find the rate of change of the angle between the ground and the ladder when the bottom of the ladder is 5 m from the wall. c) Find the rate of change of the area of the triangle bounded by the ladder, the building, and ground, when the bottom of the ladder is 5 m from the wall.