Lesson 12
More Nets, More Surface Area
Let’s draw nets and find the surface area of polyhedra.
Problem 1
Jada drew a net for a polyhedron and calculated its surface area.
![Triangular prism, dimensions and areas of faces provided.](https://cms-im.s3.amazonaws.com/aTqZDMUAzxd1eDL4TR7ZKjRQ?response-content-disposition=inline%3B%20filename%3D%226-6.1.E.PP_Image_23.png%22%3B%20filename%2A%3DUTF-8%27%276-6.1.E.PP_Image_23.png&response-content-type=image%2Fpng&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAXQCCIHWF3XOEFOW4%2F20240727%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20240727T115412Z&X-Amz-Expires=604800&X-Amz-SignedHeaders=host&X-Amz-Signature=493e87ba08bcf637d90eeb0e4e7ffcf0bbf6375c3d522f09903abe20793795c6)
- What polyhedron can be assembled from this net?
- Jada made some mistakes in her area calculation. What were the mistakes?
- Find the surface area of the polyhedron. Show your reasoning.
Problem 2
A cereal box is 8 inches by 2 inches by 12 inches. What is its surface area? Show your reasoning. If you get stuck, consider drawing a sketch of the box or its net and labeling the edges with their measurements.
Problem 3
Twelve cubes are stacked to make this figure.
![Steps, bottom row 3 cubes, middle row 2 cubes, top row 1 cube](https://cms-im.s3.amazonaws.com/YLsysrkLAdrxDKCJ8cJoJCmW?response-content-disposition=inline%3B%20filename%3D%226-6.1.E.PP.New.Image.02.png%22%3B%20filename%2A%3DUTF-8%27%276-6.1.E.PP.New.Image.02.png&response-content-type=image%2Fpng&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAXQCCIHWF3XOEFOW4%2F20240727%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20240727T115412Z&X-Amz-Expires=604800&X-Amz-SignedHeaders=host&X-Amz-Signature=460e8dc62fd779247e4833e8d9740b93600c89045cc224910f53cce7aa2d2776)
- What is its surface area?
- How would the surface area change if the top two cubes are removed?
Problem 4
Here are two polyhedra and their nets. Label all edges in the net with the correct lengths.
![Two polyhedra labeled A and B. Polyhedron A has sides labeled 5, 4, and 10. Polyhedron B has sides labeled 4, 10, 13, 13, and 13.](https://cms-im.s3.amazonaws.com/2Xfnskoyz3sRGdqASHzMTgCW?response-content-disposition=inline%3B%20filename%3D%226-6.1.E.PP_Image_8a.png%22%3B%20filename%2A%3DUTF-8%27%276-6.1.E.PP_Image_8a.png&response-content-type=image%2Fpng&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAXQCCIHWF3XOEFOW4%2F20240727%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20240727T115412Z&X-Amz-Expires=604800&X-Amz-SignedHeaders=host&X-Amz-Signature=137d13640ecb340ae883ab382b7e289b2c369b9f039c94226bb34bb3b5aaddaa)
![Figure A net of rectangular prism. Figure B rectangular pyramid.](https://cms-im.s3.amazonaws.com/a2CJ1dZxE926NEUemxsATXTZ?response-content-disposition=inline%3B%20filename%3D%226-6.1.E.PP_Image_9a.png%22%3B%20filename%2A%3DUTF-8%27%276-6.1.E.PP_Image_9a.png&response-content-type=image%2Fpng&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAXQCCIHWF3XOEFOW4%2F20240727%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20240727T115412Z&X-Amz-Expires=604800&X-Amz-SignedHeaders=host&X-Amz-Signature=f12bea6d3ce3f9239ee1fdf4f2afd9cdc522c1a3cd9faa229d70a640df7888e4)
Problem 5
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What three-dimensional figure can be assembled from the net?
- What is the surface area of the figure? (One grid square is 1 square unit.)