Use the image to answer the question.
An illustration shows a three dimensional composite figure formed by a right triangular prism placed on top of a rectangular prism. The top, right, and front faces are visible. The faces and edges that are not visible are indicated by dashed lines. The rectangular prism has a length of 12 feet and a height of 8 feet. The width of the rectangular prism is 8 feet. The edges of the hidden side face of the right triangular prism align perfectly with the edges of the hidden top face of the rectangular prism. The right triangular prism is aligned to the left of the rectangular prism. The height of the right triangular prism is not shown. The total height of the left side of the figure is 20 feet. The right triangular prism has a width of 8 feet. The hypotenuse side of the right triangular prism has a length of 15 feet.
What is the surface area of the figure?
1 answer
Surface area of the rectangular prism:
- Front and back faces: 12 ft * 8 ft = 96 sq ft
- Top and bottom faces: 12 ft * 8 ft = 96 sq ft
- Left and right faces: 8 ft * 8 ft = 64 sq ft
Total surface area of the rectangular prism: 2(96) + 2(64) = 192 + 128 = 320 sq ft
Surface area of the right triangular prism:
- The base area (triangle): 1/2 * 8 ft * 15 ft = 60 sq ft
- Right face: 8 ft * 15 ft = 120 sq ft
- Left and hypotenuse faces: not visible
Total surface area of the right triangular prism: 60 + 120 = 180 sq ft
Therefore, the total surface area of the composite figure is 320 sq ft (rectangular prism) + 180 sq ft (right triangular prism) = 500 sq ft.