# Two square pyramids with base 4 cm and slant height 5 cm are joined at their bases. What is the surface area of the resulting geometrical shape.

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### 1 Answer

Two square pyramids with base 4 cm and slant height 5 cm are joined at their base so that they share a common base. The surface area of the resulting geometric shape is the sum of their individual surfaces from which the surface area of the base has to be eliminated.

A pyramid has a surface area given by `A = B + P*L/2` where B is the area of the base, P is the perimeter of the base and L is the slant height.

For the resulting shape, the area is `A = 2*P*L/2` .

Substituting the given values of the dimensions of the pyramids, we have `A = 2*4*4*5/2`

=> `A = 4*4*5`

=> `A = 16*5`

=> `A = 80`

**The surface area of the resulting geometrical shape is 80 cm^2.**

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