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Grade 6 maths · X.6 · Volume and Surface Area

Surface area of triangular prisms from a net

Find the areas of all five faces: the two triangles and the three rectangles. For each triangle, use the two legs as the base and height.

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  1. A net folds into a triangular prism. Its two triangles are right triangles with legs 3 ft and 4 ft and longest side 5 ft. The prism is 8 ft long. The net also has three rectangles. What is the surface area of the prism in square feet?

    Answer: 108

  2. A net folds into a triangular prism. Its two triangles are right triangles with legs 3 cm and 4 cm and longest side 5 cm. The prism is 19 cm long. The net also has three rectangles. What is the surface area of the prism in square centimeters?

    Answer: 240

  3. A net folds into a triangular prism. Its two triangles are right triangles with legs 3 ft and 4 ft and longest side 5 ft. The prism is 9 ft long. The net also has three rectangles. What is the surface area of the prism in square feet?

    Answer: 120

Tip: Find the areas of all five faces: the two triangles and the three rectangles. For each triangle, use the two legs as the base and height.

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