1) We want to find the area of the triangular bases, which means both shown in the net. So, normally we would divide the area by 2 (from the formula), but since we are finding the area of two triangles, that isn't necessary.
A = 8 x 3
2) There are two different sized rectangles here. One that is repeated twice and the other that is on its own. We know that A and C are the same, and if we think about how this net is folded, we can determine that the width of A and C would be 5 cm. For both sized rectangles, the length is 12 cm. For rectangle B, we can see that its width is 8 cm.
A = (8 x 12) + (5 x 12)
3) Now that we have all of the expressions needed to find the surface area, what we need to do is evaluate each of them and add them together to find the total surface area.
Triangles = 8 x 3 = 24
Rectangles = (8 x 12) + (5 x 12) = 96 + 60 = 156
Surface area = 24 + 156 = 180 square centimeters
Hope this helps! :)
