Answer:
54.8
Explanation:
Pythagorean theorem is a^2+b^2=c^2.
Plug the given values in to get 61^2+b^2=82^2
61^2 is 3,721 and 82^2 is 6,724.
6,724-3,721 is 3,003.
The square root of 3,003, rounded to a reasonable value, is 54.8.
The length of AC is 54.8.