Radians Definition

noun
  • geometry
    a unit of measurement of angles.
    "a full rotation around the circle is 2π radians."
All terms

Explanation

Radians are a unit of measurement of angles. To measure an angle in radians, divide the arc length by the radius.

Radians Definition

A half rotation or degrees is (pi) radians, where is approximately equal to . The value of is defined by the circumference of any circle divided by its diameter.

Typically, angles measured in radians are written in terms of . Read more about the radian angle system on this page.

Related Terms

Angle

An angle is a measure of rotation or turning and is usually measured in degrees or radians. In geometry, an angle is the figure formed by two rays, sharing a common endpoint called the vertex.

Circle

A circle is a basic shape used throughout mathematics. A circle is defined as a shape where every point along its perimeter is an equal distance from its center.

Degrees

Degrees are a unit of measurement for angles, representing the rotation between two rays. The degree angle system divides a full rotation into 360 units called degrees.

Links

Radian Angle System

Radians are a unit that measures angle using the radius of a circle. One radian is equal to the amount of rotation required to travel the length of one radius along the circumference of the circle.

Degree Angle System

Degrees are a unit of measure for angles. A full rotation is equal to 360 degrees. In the XY Cartesian Coordinate System, degrees are measured starting from the rightmost edge of the circle.

π (pi)

The Greek letter π (pi) is a geometric constant approximately equal to 3.1416. Its value is equal to the length of any circle's circumference divided by its diameter.

τ (tau)

The circle constant τ (tau) is a geometric constant approximately equal to 6.283. The numeric value is defined as the length of any circle's circumference divided by the length of its radius.