Okay. So the two sides f the very end right triangle are 10 and 8, 10 is the hypothesis. To find the missing side, you can use the Pythagorean Theorem, which is a² + b² = c². So just fill in the values (c is the hypothesis).
8² + b² = 10² Square the numbers.
64 + b² = 100 Subtract.
b² = 36 Find the square roots.
b = 6
So now you know that the bottom of the right triangle is 6 ft. Now double that to find the base of the whole entire acute triangle, so 12 inches. And you know that the base of the design is made of four triangles, so do 12 x 4. The base of the design is 48 ft.