Answer:
Exact Surface Area = [tex]480+32\sqrt{3}[/tex]
Approximate Surface Area = 535.425625842204
Round the approximate value however you need to
Units are in square centimeters.
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Work Shown:
You have the 160 portions correct since 20*8 = 160.
The other pieces are equilateral triangles, in which we use the formula
[tex]A = \frac{\sqrt{3}}{4}x^2[/tex]
where x is the side length of the triangle. Plug in x = 8 to get
[tex]A = \frac{\sqrt{3}}{4}x^2\\\\A = \frac{\sqrt{3}}{4}8^2\\\\A = \sqrt{3}*\frac{1}{4}*64\\\\A = \sqrt{3}*16\\\\A = 16\sqrt{3}\\\\[/tex]
That's the exact area of one triangle, but we have two of them. Double the result to get [tex]2*16*\sqrt{3} = 32\sqrt{3}[/tex]
The total surface area is the sum of all the smaller areas
[tex]160+160+160+32\sqrt{3} = 480+32\sqrt{3}[/tex]
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The exact surface area is [tex]480+32\sqrt{3}[/tex] square cm.
Using a calculator, you should get [tex]480+32\sqrt{3} \approx 535.425625842204[/tex]
Round this however you need to.
