Radian

usgb/ˈreɪdiən/
noun

A unit for measuring angles. One radian is the angle made when the length of the radius is wrapped along the circle's edge.

The angle of a full circle is approximately 6.28 radians.
Visual representation of "radian" - A unit for measuring angles. One radian is the angle made when the length of the radius is wrapped along the circle's edge.

Often appears as...

  • convert degrees to radians
  • measure in radians

Usage tips

Technical

Definition 1 of 1
Visual representation of "radian"
LampPro Tip 1/3

Visualize the Circle

Imagine wrapping a circle's radius along its edge to see the radian angle it creates.

Illustration for Visualize the Circle
If you visualize a pizza slice, one radian would be a slice where the crust's arc is equal to the radius of the pizza.
LampPro Tip 2/3

Conversion Relation

Understand the conversion between radians and degrees, since 180 degrees is equal to π radians.

Illustration for Conversion Relation
To find an angle in radians, divide the degrees by 180 and multiply by π.
LampPro Tip 3/3

Radians in Formulas

Know that radians are used in mathematical expressions involving trigonometry and calculus.

Illustration for Radians in Formulas
The formula for the area of a sector is (1/2)*r^2*θ, where θ is the angle in radians.
Visual representation of the word "Radian"

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