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Volume

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The volume of an object is a measure of the amount of space that it occupies. Note that volume only applies to three-dimensional figures.

Contents

Finding Volume

This section covers the methods to find volumes of common Euclidean objects.

Prism

The volume of a prism of height h and base of area b is b\cdot h.

Pyramid

The volume of a pyramid of height h and base of area b is \frac{bh}{3}.

Sphere

The volume of a sphere of radius r is \frac 43 r^3\pi.

Cylinder

The volume of a cylinder of height h and radius r is \pi r^2h. (Note that this is just a special case of the formula for a prism.)

Cone

The volume of a cone of height h and radius r is \frac{\pi r^2h}{3}. (Note that this is just a special case of the formula for a pyramid.)

Irregular objects

The volume of an object defined by an upper bound of f(x,y,z) in the Cartesian three-space can be found using a triple integral: \int_{a_z}^{b_z}\int_{a_y}^{b_y}\int_{a_x}^{b_x}f(x,y,z)\text{ dx dy dz}, where (a_z,b_z) are the bounds of z and similar bounds are defined for x and y.

Problems

Introductory

Intermediate

  • A tripod has three legs each of length 5 feet. When the tripod is set up, the angle between any pair of legs is equal to the angle between any other pair, and the top of the tripod is 4 feet from the ground. In setting up the tripod, the lower 1 foot of one leg breaks off. Let h be the height in feet of the top of the tripod from the ground when the broken tripod is set up. Then h can be written in the form \frac m{\sqrt{n}}, where m and n are positive integers and n is not divisible by the square of any prime. Find \lfloor m+\sqrt{n}\rfloor. (The notation \lfloor x\rfloor denotes the greatest integer that is less than or equal to x.) (Source)

Olympiad

See Also

Looking for a challenging geometry text? Preparing for MATHCOUNTS or the AMC exams? Check out Art of Problem Solving's Introduction to Geometry by Richard Rusczyk.
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