Use a net to find the surface area of the right triangular prism shown below: three rectangles next to each other with a width of 7 feet. the first and second rectangles length are unknown, and the last is 10 feet long. there are two right triangles above and below the last rectangle. one is labeled with a base of 6 feet and a height of 8 feet. 198 square feet 216 square feet 270 square feet 280 square feet