3a. A ladder 25 feet long is leaning against the wall of a house. The base of the ladder is being pulled away from the wall at a rate of 2 feet per second. How fast is the top of the ladder moving down the wall when its base is 15 feet from the wall. 3b. Consider the triangle formed by the side of the house, the ladder and the ground. Find the rate at which the area of the triangle is changing when the base of the ladder is 15 feet from the wall.A cone has a radius of 8 inches at its base and a total height of 12 inches. If water is filling up the cone at a rate of 5 cubic inches per minute, how fast is the radius changing when the water level is 7 inches