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10. To do that, find the surface area of 3 non-congruent rectangles, and then multiply by 2:

\(2(10\cdot4+10\cdot2+2\cdot4) = 136\)

11. To find the surface area of that, find the area of one of the 4 congruent triangles, multiply it by 4, and then add the area of the square:

\(\frac{6\cdot9}{2}\cdot4+6\cdot6=144\)

This might help: https://courses.lumenlearning.com/math4libarts/chapter/surface-area/#:~:text=The%20area%20of%20the%20net,of%20triangle%20A%20by%202.

textot Feb 25, 2021