Q:
# What is a radius?

**The radius of a circle is the length of a line segment from its center to its outer edge.** The same definition also applies to the radius of a sphere. Alternatively, a shape's radius can be defined as half of its diameter. The diameter is the length of a straight line segment passing through a circle or sphere's center.

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The radius is commonly used in many areas of geometry. For example, the radius is required to calculate the area of a circle or sphere, as well as the volume. For shapes that do not have an obvious center, the word "radius" can refer to its circumradius, meaning the radius of a circle that passes through all vertices. In circles and spheres, the radius equals the diameter when multiplied by two. Measurements relating to diameter and radii are in linear units, such as inches and centimeters.

The word originates from Latin "radius," meaning the spoke of a chariot wheel. The plural form of "radius" can be either the Latin "radii" or the conventional English "radiuses." The typical mathematical variable name and abbreviation for radius is "r." Occasionally, the word "radius" is used to refer to the line segment itself rather than the length.

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Q:
## How do you find the domain and range of a circle?

A: The domain of a circle is the X coordinate of the center of the circle plus and minus the radius of the circle. The range of a circle is the Y coordinate o... Full Answer >Filed Under: -
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## How do you measure diameter?

A: If the radius of the circle is known, the diameter formula is diameter=2R, where R equals the circle's radius. If the circumference of the circle is known,... Full Answer >Filed Under: -
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## How do you find the area of a sector of a circle?

A: The equation for the area of a circle is pi times the square of the radius or A = πr2. Calculating the area of a sector involves figuring out what fraction... Full Answer >Filed Under: -
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## What are some ways to measure a radius?

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