Step-by-step explanation:
it looks like this is a regular (right) triangular prism with 3 equal side areas and one bottom area.
the surface area of the pyramid is the sum of all 4 of these areas.
all these areas are triangles.
the area of a triangle is
baseline × height / 2
in our case
1 side area is 6×8.2/2 = 3×8.2 = 24.6 yd²
all 3 side areas together are 24.6×3 = 73.8 yd²
the bottom triangle is
6×5.2/2 = 3×5.2 = 15.6 yd²
so, the total surface area is
73.8 + 15.6 = 89.4 yd²
