Equation of Limaçon of Pascal/Cartesian Form

Theorem
The limaçon of Pascal can be defined by the Cartesian equation:
 * $\paren {x^2 + y^2 - a x}^2 = b^2 \paren {x^2 + y^2}$

Also see

 * Equation of Limaçon of Pascal/Polar Form