There are 3 triangles for the sides. The area for a triangle is one half base times height. So we are doing one half of 9 times 9. This is 40.5. Since there are 3 of them we can just multiply 40.5 times 3 to get 121.5. And now to solve for the base triangle, it is one half of 9 times 7.8. We get 35.1. Now add together 121.5 and 35.1. We get 156.6. Now since this is surface area it is meters squared.
