Calxsolver
Subject:  Trigonometry

Radian

The natural unit of angle: a full turn is 2π radians.

One radian is the angle subtended at the centre of a circle by an arc equal in length to the radius. The conversion 1° = π/180 rad makes radians the unit of choice in calculus, where the derivative formulas for sin and cos assume the input is in radians.

Formula

θ (rad) = θ (deg) × π / 180

Used in

Angle Converter Convert degrees and radians, with reference angle. Trig Function Evaluator Evaluate sin, cos, tan, csc, sec or cot of an angle.

See also

Sine In a right triangle, the ratio of the side opposite an angle to the hypotenuse. Cosine In a right triangle, the ratio of the side adjacent to an angle to the hypotenuse.