Answer:
It will take 39.27 gallons to repaint the barn.
Explanation:
The image of the setup is obtained from online and attached to this solution.
The rectangular prism is a cuboid of
Length = 84 ft
Breadth = 38 ft
Height = 20 ft
And the triangular prism on top of the rectangular prism has a vertical height of 12 ft.
The surface area of the composite structure that is available for painting include the 4 sides of the top triangular prism and the four sides of rectangular prism
Two of the faces of the triangular prism are triangles with base of 38 ft and height of 12 ft.
The other two faces of the triangular prism are rectangles with length 84 ft and breadth of the hypoteneuse of the right angled triangle on top.
B² = 12² + 19²
B = 22.47 ft
Total Surface area of the faces of the rectangular prism is then
2×(84×20) + 2×(38×20) = 4880 ft²
Total surface area of the faces of the triangular prism is then
2×(0.5×12×38) + 2×(84×22.47) = 4,230.96 ft²
Total surface area = 4880 + 4230.96 = 9110.96 ft²
1 gallon of paint = 232 ft²
x gallons of paint = 9110.96 ft²
x = (1×9110.96/232) = 39.27 gallons.
Hope this Helps!!!