Answer:
12 feet
Explanation:
when you have c (the hypotenuse) and a (the opposite side) but you need to find b (the base) you have to flip around the theorm from a^2 + b^2 = c^2 to c^2 - a^2 = b^2.
then you plug in your numbers: 20^2 - 16^2 = b^2
then you solve the exponents: 400 - 256 = b^2
and subtract: 144 = b^2
lastly you square root both sides to get your answer: 12 = b
hope this helped :))