First, let’s get the area of the base. To do that, we multiply 9 times 5, which gets us 45. Next, for the two sides of the triangular prism, take 7 times 5, which is 35, and multiply that by two, getting 70. Next, for the two triangles, we have to use the triangle surface area formula, which is 1/2•base•height. So, take the base and the heigh, 9, and 6, and you get 54. Since there are two triangles, we don’t have to divide it by 2. So, we add all of our sides, 54, 70, and 45, and we get 169 sq cm.
