Complex sentence: Another important special case is when the three given circles are tangent to each other, René Descartes found an equation relating the radii of the solution circles and those of the given circles; this equation is now known as Descartes' theorem.
Split into simpler sentences: Another important special case is when the three given circles are tangent to each other. In this case, René Descartes found an equation relating the radii of the solution circles and those of the given circles; this equation is now known as Descartes' theorem.