Use the pythagorean theorem (a^2 + b^2 = c^2).
48^2 + b^2 = 50^2 (the hypotenuse is always plugged in as the "c" value.
This simplifies to 2304 + b^2 = 2500.
Subtract 2304 from 2500 and you get b^2 = 196.
Take the square root of 196, which becomes b=14.
The answer is 14 ft