# Difference between revisions of "Circle"

From Conservapedia

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− | [[Image:265px-Circle Area svg.png|right|thumb|Area of the circle = | + | [[Image:265px-Circle Area svg.png|right|thumb|Area of the circle = <math>\pi</math> × area of the shaded square]] |

− | A circle is the [[set]] of all the points in a given [[plane]] that are the same distance from a given [[point]] called the center. | + | |

+ | A '''circle''' is the [[set]] of all the points in a given [[plane]] that are the same distance, called the [[radius]], ''r'', from a given [[point]] called the center. | ||

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+ | A circle may also be defined [[algebra]]ically, as the solutions to an equation of the form: | ||

+ | |||

+ | :<math>x^2 + y^2 = r^2</math> | ||

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+ | The measure of the line that forms the circle, or circumference, is given by: | ||

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+ | :<math>C = 2\pi*r</math> | ||

+ | |||

+ | The area inside the circle is calculated using the formula: | ||

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+ | :<math>A = \pi*r^2</math> | ||

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+ | A circle is a [[conic section]], the intersection of a plane with a cone such that the plane is perpendicular to the axis of the cone. | ||

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+ | Circles can readily be constructed by using a fixed distance between a pencil point and the center. A [[compass]] is a tool for doing this easily. | ||

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+ | A circle with <math>r = 1</math> is called the ''unit circle'', and is used extensively in [[trignometry]]. | ||

[[Category:Geometry]] | [[Category:Geometry]] | ||

+ | [[category:mathematics]] |

## Revision as of 13:05, 22 April 2007

A **circle** is the set of all the points in a given plane that are the same distance, called the radius, *r*, from a given point called the center.

A circle may also be defined algebraically, as the solutions to an equation of the form:

The measure of the line that forms the circle, or circumference, is given by:

The area inside the circle is calculated using the formula:

A circle is a conic section, the intersection of a plane with a cone such that the plane is perpendicular to the axis of the cone.

Circles can readily be constructed by using a fixed distance between a pencil point and the center. A compass is a tool for doing this easily.

A circle with is called the *unit circle*, and is used extensively in trignometry.