The point P with polar coordinates (r,\theta) is such that OP=r and the angle between the x-axis and the line through OP is \theta measured counter clockwise. Equivalently if P has Cartesian coordinates (x,y) then x=r\cos \theta and y=r\sin \theta.
The question asks for an explanation of the features of the graph. If you want to use a software package to sketch the graph you may want to download the shareware graphing software Graphmatica .
Sketch the graph of xy(x^2 - y^2) = x^2 + y^2 consisting of four curves and a single point at the origin. Convert to polar form. Describe the symmetries of the graph.