To work out the surface area of a triangular prism:
Base: l x w
= 4 x 7
= 28 feet
Top: l x w
= 5 x 7
= 35 feet
Two sides: 1/2 x b x h
= 1/2 x 4 x 3
= 6 + 6 (for the other side)
= 12 feet
Left side: l x w
= 3 x 7
= 21
Add all of them up:
= 28 + 35 + 12 + 21
= 96 square feet
