Chapter 3.3, Problem 45E

Related Rates A baseball diamond is a $90$- foot by $90$- foot square. (See Fig. 9). A player runs from first to second base at the speed of $22$ feet per second. How fast is the player’s distance from third base changing when he is halfway between first and second base? [Hint: If $x$ is the distance from the player to second base and $y$ is his distance from third base, then $x^2+{90}^2=y^2$.]