Answer
$\approx84.9$ feet
Work Step by Step
In Exercise 48 we used the Pythagorean theorem to find the hypotenuse of the right triangle. Instead we can use proportions and the information in Exercise 47 to obtain the same answer.
We know that in Exercise 47, a major league baseball diamond has sides of length 90 feet and the hypotenuse (length from home plate to 2nd base) of 127.3 feet. We can use this information to set up a proportion with the diamond in Exercise 48:
$\displaystyle \frac{x~(hypotenuse)}{60~feet}=\frac{127.3~feet}{90~feet}$
Cross-multiply:
$90x=127.3*60$
$90x=7638$
$x=7638/90$
$x\approx84.9$ feet
This matches our answer to Exercise 48.