A polar coordinate system, gives the co-ordinates of a point with reference to a point 0 and a half line or ray starting at the point O. We will look at polar coordinates for points in the xy-plane, using the origin (0, 0) and the positive x-axis for reference. A point P in the plane, has polar coordinates (r, 6), where r is the distance of the point from the origin and θ is the angle that the ray |OP| makes with the positive x-axis.
极坐标下方程的图像
The graph of an equation in polar coordinates r= f(θ) or F(r,θ)= 0 consists of all points P that have at least one polar representation (r, 0) whose coordinates satisfy the equation.