So for this, you'll be using the pythagorean theorem to solve for the height.

Solve the exponents to get

Subtract 81 on each side to get

Square root each side, and your answer should be

or 13.23 ft
6 units as a mixed number will get you to 16
Volume of a pyramid is calculated by L×W×H÷3. Which means 81× 10× 10 ÷ 3
81 × 10 × 10 = 8100 ÷ 3
So the answer is 2700.