The answer is 13, i got this by using the pythagorean theorem. a^2 + b^2 = c^2. in this case it would be 84^2 + b^2 = 85^2. then that would turn into 7056 + b^2 = 7225, subtract both sides by 7056 to get b^2 = 169, then square 169 to get 13 :)
Perimeter: 9+9+8+8= 34 ft.
Area: 9*8= 72 ft²
Looks like a good question, using the mathematical term of "radical."
<span> The surface area of a right prism can be calculated using the following formula: SA 5 2B 1 hP, where B is the area of the base, h is the height of the prism, and P is the perimeter of the base. The lateral area of a figure is the area of the non-base faces only.</span>