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 10 feet. the first and second rectangles length are unknown, and the last is 15 feet long. there are two right triangles above and below the last rectangle. one is labeled with a base of 9 feet and a height of 12 feet. 104 square feet 412 square feet 468 square feet 504 square feet