The area of the base (B) of a triangular pyramid is 28 cm. The perimeter (p) is 20 cm, and the slant height (S) is 5 cm. Determine the pyramid's surface area.

The pyramid's surface area is 78 square centimeters

Step-by-step explanation:

The formula of the surface area of a pyramid is S.A = A + p s, where

∵ The area of the base of a triangular pyramid is 28 cm²

∴ A = 28 cm²

∵ The perimeter of the base is 20 cm

∴ p = 20 cm

∵ The he slant height is 5 cm

∴ s = 5 cm

- Substitute these values in the formula of the surface area

   above to find it

∵ S.A = 28 + (20)(5)

∴ S.A = 28 + 50

∴ S.A = 78 cm²

The pyramid's surface area is 78 square centimeters