# Radians

Radians are a unit that measure rotation using the radius of a circle. One full rotation is equal to the length of the circumference, divided by the length of the radius. This number is independent of the size of the circle and its value is approximately .

This number is so useful that we will represent a full rotation with the symbol Tau as . Other math references use the constant PI, as as , to represent a half rotation.

## Examples

### Convert Angle from Degrees to Radians

To convert degrees to radians, multiply the angle by pi and then divide by 180.

### Convert Angle from Radians to Degrees

To convert an angle from radians to degrees divide by pi and then multiply by 180.

### Convert Point From Polar Coordinates to Cartesian Coordinates

To convert a point from the Polar Coordinate System to the Cartesian Coordinate System you can use the definition of sine and cosine to solve for the x and y component of the corresponding point.

### Memorize Unit Circle Chart

To memorize the unit circle chart, you can learn the positions of the points at the angles 30 degrees and 45 degrees, then use symmetry to fill in the rest of the points.