radiaan

Radian is a unit of angle measurement. It is defined such that a full circle contains 2π radians. One radian is the angle subtended at the center of a circle by an arc whose length is equal to the radius of the circle. This means that if you take a piece of string the length of the radius and wrap it around the circumference of the circle, the angle formed at the center is one radian.

The radian is the standard unit of angular measure used in many areas of mathematics and physics, particularly in calculus and trigonometry. Its use simplifies many formulas. For example, the arc length s of a sector of a circle with radius r and central angle θ (measured in radians) is given by the simple formula s = rθ. Similarly, the area A of such a sector is A = (1/2)r²θ.

To convert between degrees and radians, one can use the relationship that 180 degrees is equal to π radians. Therefore, to convert from degrees to radians, multiply by π/180. To convert from radians to degrees, multiply by 180/π. For instance, 90 degrees is equal to π/2 radians, and 360 degrees is equal to 2π radians. The radian is a dimensionless quantity, as it is a ratio of two lengths (arc length to radius).