The perimeter of the base of a square pyramid is 40 feet. The slant height of the pyramid is 12 feet. Find the surface area of the pyramid.

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  340 ft^2

Step-by-step explanation:

The length of one side is 1/4 of the perimeter, so is 10 ft.

The area of the base is the square of the length of the side:

  base area = (10 ft)^2 = 100 ft^2

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The lateral area is the area of four triangles, each with a base of 10 ft and a height of 12 ft.

  lateral area = 4(1/2)(10 ft)(12 ft) = 240 ft^2

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The total surface area is the sum of the base area and the lateral area:

  surface area = base area + lateral area

  surface area = (100 ft^2) +(240 ft^2) = 340 ft^2