SOLUTION: http://diagnostic.achievementseries.com/cdn//1/_graphics_math_18852/d7363902-5a4d-4f49-8595-582132103a8b.gif For the square pyramid above, find the surface area of the square pyra

Algebra ->  Trigonometry-basics -> SOLUTION: http://diagnostic.achievementseries.com/cdn//1/_graphics_math_18852/d7363902-5a4d-4f49-8595-582132103a8b.gif For the square pyramid above, find the surface area of the square pyra      Log On


   



Question 1013509: http://diagnostic.achievementseries.com/cdn//1/_graphics_math_18852/d7363902-5a4d-4f49-8595-582132103a8b.gif
For the square pyramid above, find the surface area of the square pyramid, if it has a slant height of 5 m.
If you can't see the picture, the bases on each side are 8m.
I tried to do this problem but got 88m.
My choices are 320m^2, 160m^2, 144m^2, 64m^2.
What did i do wrong?
Thanks.

Answer by rothauserc(4718) About Me  (Show Source):
You can put this solution on YOUR website!
The area of the square base is s^2 where s is the length of the base
The area of one triangle is (s * l) / 2 where l is the slant height
There are 4 four triangles, 4 * (s * l) / 2 = (2 * s * l)
Therefore,
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The surface area(SA) of a square pyramid is calculated by the following formula:
SA = s^2 + (2 × s × l), where s is the length of a side and l is the slant height
SA = 8^2 + ( 2 * 8 * 5 )
SA = 64 + 80
SA = 144m^2