check the picture below.
so the triangular prism is really just 3 rectangles and 2 right-triangles,
now, we know the base of one of the triangles is 2.6, what's its height?
since it's a right-triangle, we can simply use the pythagorean theorem to get "h".
so, we can now, simply get the area of both of the triangles and the three rectangles and sum them up, and that's the area of the triangular prism.
