#### Problem 20E

20. A baseball diamond is a square with side $90 \mathrm{ft}$. A batter hits the ball and runs toward first base with a speed of $24 \mathrm{ft} / \mathrm{s}$.

(a) At what rate is his distance from second base decreasing when he is halfway to first base?

(b) At what rate is his distance from third base increasing at the same moment?