Principia Prop. I.7 cor. 2

Figure for Newton Principia Prop. I.7 cor. 2
The force acting on P revolving around S is to the force on R revolving around S as the square RP×SP is to SG³, that is,[br][br][math]F_{S}:F_{R}::\frac{RP^2×SP}{SG^3}[/math]
– Alexis Doval

Information: Principia Prop. I.7 cor. 2