The radius (plural radii) that a circle is any kind of line segment that has one endpoint top top the facility of the circle and also the various other endpoint on the circle\"s circumference. It can additionally be defined as the distance from the center of a circle come a point on the circumference. A circle contains infinitely countless radii.

You are watching: How many radii does a circle have The spokes on the wheel of a bicycle wheel room radii of its one rim. The radius the a circle is one-half the size of its diameter. The 2 radii of size r, shown over for the circle, lied on that diameter, d. This way that d = 2r or .

## Central angles

A main angle is created by 2 radii the a circle. Sides OA and OB of central angle AOB are formed by radius OA and also radius OB.

A radius the a continual polygon is the radius that its circumcircle, i beg your pardon is a circle the intersects every vertex of the polygon. A radius for a constant pentagon is referred to as a circumradius. Circumcircle ns of the regular pentagon above has 5 radii, every of i m sorry are developed by a heat segment that has actually one endpoint on point P and also the other on one of the 5 vertices that the pentagon.

## Radius together an edge unit

In the examine of Trigonometry, the radius that a circle is supplied to measure an angle v a unit the measure dubbed a radian. If the size of an arc is equal to the size of the radius, the main angle subtended by the arc is 1 radius unit, or 1 radian. Generally, the measure of an angle in radians is part multiple that the length of the radius. For central angle QPR above, the measure of arc QR is equal to the size of the radius, so∠QPR = 1 radian. For main angle QPR above, the measure of arc QR is or around 2.1 time the radius, therefore  