One of the equilateral triangular faces of a regular square pyramid is glued to a triangular face of a congruent regular square pyramid. If the side length of the regular square pyramid is 8, find the surface area of the new solid.

Respuesta :

Answer:

128 + 96√3 or 294.28 unit^3 to the nearest hundredth.

Step-by-step explanation:

The surface area of one of the pyramids = area of the square base + area of the 4 equilateral triangles

=  8^2 +  4 * 1/2 * 8 * 4√3

= 64 + 64√3.

So the area of the new solid =  2(64 + 64√3) - area of 2 triangles

=  2(64 + 64√3) - 32√3

= 128 + 128√3 - 32√3

= 128 + 96√3.

The surface area of the new figure is given by the sum of the surface area of the exposed surface.

The surface area of the new solid is 128 + 96·√3 square units.

Reason:

The given parameters are;

The side length of the base of the square pyramid = 8

Area of each triangular surface = 0.5 × 8 × 8 × sin(60°) = 16·√3

The area of the six exposed triangular surfaces of the new solid is given as follows;

A₆ = 6 × 16·√3 = 96·√3

Area of the two square bases, [tex]A_{sb}[/tex] = 2 × 64 = 128

The surface area of the new solid, A = [tex]A_{sb}[/tex] + A₆

∴The surface area of the new solid, A = 128 + 96·√3 square units

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