Parametric Equations and Polar Coordinates
The polar coordinate system consists of a pole and a polar axis. The pole is a fixed point, and the polar axis is a directed ray whose endpoint is the pole. Every point in the plane of the polar axis can be specified according to two coordinates: r , the distance between the point and the pole, and θ , the angle between the polar axis and the ray containing the point whose endpoint is also the pole.
To convert equations between polar coordinates and rectangular coordinates, consider the following diagram:
To convert from rectangular to polar coordinates, use the following equations: x = r cos(θ), y = r sin(θ) . To convert from polar to rectangular coordinates, use these equations: r = sqrtx 2+y 2, θ = arctan() .