Answer:
340.8cm^2
Explanation:
So surface area is basically the area of all the sides combined. And we know that the area of a triangle is 1/2bh, and for a rectangle it is LW. So there are three congruent rectangles, and one of those rectangle's area is 72 ( 6 x 12), so you can multiply that by 3 to find all three rectangles, which is 216. We also know that the two triangles are congruent. and the base is 12, and height is 10.4, so 12 x 10.4 is 124.8.
We take the total of the rectangles and the triangles to find the total surface area:
216 + 124.8 = 340.8cm^2