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Volume

From AoPSWiki

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

Want to learn how to tackle those tough MATHCOUNTS and AMC counting and probability problems? Check out Art of Problem Solving's Introduction to Counting & Probability by David Patrick.
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