1. A kite 50ft above the ground moves horizontally at a speed of 2ft/s. At what rate is the angle between the string and the horizontal decreasing when 200ft of string has been let out?
2. A 12 foot ladder is leaning against a wall. If the top slips down the wall at a rate of 2 ft/s, how fast will the foot be moving away from the wall when the top is 10 feet above the ground?
3. A spherical balloon is to be deflated so that its radius decreases at a constant rate of 7 cm/min. At what rate must air be removed when the radius is 9 cm?