๐Ÿ“– Math Dictionary

Radius

/RAY-dee-us/

Definition

The radius is the distance from the center of a circle to any point on its edge. It is exactly half the diameter. All radii (plural) of a circle are equal in length.

๐Ÿ’กExample

If a circle has a diameter of 10 cm, its radius is 10 รท 2 = 5 cm. The circumference formula C = 2ฯ€r uses the radius. Area formula A = ฯ€rยฒ also uses radius.

๐ŸŽ“Used in Grades

Grades 4-10KS2 to GCSEร…rskurs 4-9

๐Ÿ”—Related Terms

Diameter

๐Ÿ“šLearn More

circles โ†’area of circle โ†’circumference โ†’

Practice with Radius

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