Geometry: Area and Volume of Solids

On this page we hope to clear up any problems that you might have with finding the area or volume of solids.  Throughout our schooling we have had to know many different formulas dealing with finding the volume of solids.  We found that it was helpful to have a reference that had each of the formulas listed so we could easily reference it when we needed a formula or forgot it.  That is how this page is laid out, with one special addition - figures that accompany each formula to help make the formula make more sense.  Read on or follow any of the links below to start understanding how to find the volume or area of solids!

Area of prisms
Volume of prisms
Pyramids
Cylinders
Cones
Spheres
Quiz on area and volume of solids


Area of Prisms

There are special formulas that deal with prisms, but they only deal with right prisms.  Right prisms are prisms that have two special characteristics — all lateral edges are perpendicular to the bases, and lateral faces are rectangular.  This figure depicts a right prism.

Right Prism Area
The lateral area L (area of the vertical sides only) of any right prism is equal to the perimeter of the base times the height of the prism (L = Ph).

The total area T of any right prism is equal to two times the area of the base plus the lateral area.

Formula: T = 2B + Ph
Example: Example Figure

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Volume of Prisms

Right Prism Volume Postulate
The volume V of any right prism is the product of B, the area of the base, and the height h of the prism.

Formula: V = Bh
Example: Example Figure

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Pyramids

A pyramid is a polyhedron with a single base and lateral faces that are all triangular.  All lateral edges of a pyramid meet at a single point, or vertex.

Pyramid Volume Theorem
The volume V of any pyramid with height h and a base with area B is equal to one-third the product of the height and the area of the base.

Formula: V = (1/3)Bh
Example: Example Figure

A regular pyramid is a pyramid that has a base that is a regular polygon and with lateral faces that are all congruent isosceles triangles.

Regular Pyramid Area Theorem
The area L of any regular pyramid with a base that has perimeter P and with slant height l is equal to one-half the product of the perimeter and the slant height.

Formula: L = .5Pl
Example: Example Figure

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Cylinders

Cylinder Volume Theorem
The volume V of any cylinder with radius r and height h is equal to the product of the area of a base and the height.

Formula: V = (PI)(r^2)h
Example: Example Figure

For any right circular cylinder with radius r and height h, the total area T is two times the area of the base plus the lateral area (2(PI)rh).

Formula: T = 2(PI)rh + 2(PI)r^2
Example: Example Figure

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Cones

Cone Volume Theorem
The volume V of any cone with radius r and height h is equal to one-third the product of the height and the area of the base.

Formula: V = (1/3)(PI)(r^2)h
Example: Example Figure

Cone Area Theorem
The total area T of a cone with radius r and slant height l is equal to the area of the base plus PI times the product of the radius and the slant height.

Formula: T = (PI)rl + (PI)r^2
Example: Example Figure

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Spheres

Sphere Volume and Area Theorem
The volume V for any sphere with radius r is equal to four-thirds the product of PI and the cube of the radius.  The area A of any sphere with radius r is equal to 4(PI) times the square of the radius.

Volume Formula: V = (4/3)(PI)r^3
Area Formula: A = 4(PI)r^2
Example: Example Figure

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Take the quiz on area and volume of solids.  The quiz is very useful for either review or to see if you've really got the topic down.


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Math for Morons Like Us -- Geometry: Area and Volume of Solids
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