Have you learned about how to find the hypotenuse yet? If so:
The Pythagorean Theorum states that
a^2+b^2= c^2 (sorry, that was the best way I could type squaring numbers, but ^2 means to square the number)
If you plug it in:
10^2 + 60^2 = 65^2
After solving:
100 + 3,600 = 4225
3,700 = 4225
3,700 and 4,225 are NOT equal, so therefore, it is not possible to make a right triangle using the lengths of 10 ft, 65 ft, and 60ft