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Surface Area of a Right Pyramid

A right pyramid is a solid 3D object with a base that is a regular polygon (all side lengths are the same), and with a vertex that is directly above the center of the base.

Surface Area

The surface area of a right pyramid can be broken down into the following:
  • Area of the base Since this is a regular polygon, we can calculate the area by breaking it up into equal triangles
  • Area of the triangular sides Each trigular side=Side length of polygon×Slant height2\text{Each trigular side}=\dfrac{\text{Side length of polygon}\times\text{Slant height}}{2}
To find the surface area, we add up the area of the base and the area of the triangular sides.

Square-Based Pyramid

The surface area of a square-based pyramid with base side length bb and a slant height of LL is
S.A.square-based pyramid=b2+2bL\large\boxed{\text{S.A.}_\text{square-based pyramid}=b^2+2bL}

Practice: Surface Area of a Right Pyramid

What is the surface area of the following right pyramid?

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Volume of a Right Pyramid

The volume of a right pyramid is 13\dfrac{1}{3} the volume of the prism with the same base and the same height.

Vpyramid=13(Area of the base×height)\large\boxed{V_\text{pyramid}=\dfrac{1}{3}\left(\text{Area of the base}\times \text{height}\right)}

Practice: Volume of a Right Pyramid

What is the volume of the following right pyramid?

Practice: Right Pyramid

A right pyramid has a base that is a regular hexagon (6-sided polygon) with side length 10 cm and base area of 150 cm2. The height of the pyramid is 12 cm.

a) Determine the slant height of the pyramid.

b) Determine the surface area of the pyramid.

c) Determine the volume of the pyramid.

Practice: Right Pyramid

A fish tank company has 2 new designs -- a rectangular-base prism tank and a regular octagonal-base (8 sided polygon) pyramid tank. The dimensions of the tank are shown in this diagram.

The volumes of the two tanks are to be equal, and both tanks are to be produced using the same glass material. Which tank will require less glass to produce?