A baseball diamond is a square with side 90 feet. A batter hits the ball and runs toward first base with a speed of 21 ft/s. (a) At what rate (in ft/s) is his distance from second base decreasing when he is halfway to first base? (Round your answer to one decimal place.)
(b) At what rate (in ft/s) is his distance from third base increasing at the same moment? (Round your answer to one decimal place.)