Polar Coordinates

From Math Images

Polar Coordinates are coordinates which locate points by their distance from the origin and their rotation from the positive x-axis. Traditionally, $r$ represents distance from the origin and $\theta$ represents rotation from the positive x-axis.

For example, the point $(x,y) = (1/\sqrt{2},1/\sqrt{2})$ is 1 unit from the origin (as can be seen by the Pythagorean Theorem) and is a rotation of $\pi/4$ from the positive x-axis, so can be represented in polar form by: $(r,\theta)=(1,\pi/4)$ .