Find the surface area of the composite figure

Answer: 1108 in^2

 

Explanation:

Let's first find the surface area of the top triangular prism part.

There are two 11x20 rectangles, and two triangles with base 12 and height 9.

 

For the rectangular prism on bottom, we have one rectangle of 12x20, two of 20x5, and two of 12x5.

Adding everything up, 11x20+11x20+12x9/2+12x9/2+12x20+20x5+20x5+12x5+12x5 is pretty tedious, but managable.

440+108+240+200+120=548+560=1108 in ^2.

 

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