Answer:
The fence is 18.9 ft long.
Step-by-step explanation:
If you were to create a diagonal line from corner to corner with a square that is 10x16ft, you would have a triangle with 2 known sides and an unknown value. In this case, because you are making a 90° triangle, you can use Pythagorean Theorem:
a^{2} + b^{2} = c^{2}
10^{2} + 16^{2} = c^{2}
100 + 256 = c^{2}
356 = c^{2}
√356 = c
18.9 = c