<Dl> <Dd> ε = r max − r min r max + r min . (\ displaystyle \ varepsilon = (\ frac (r_ (\ max) - r_ (\ min)) (r_ (\ max) + r_ (\ min))).) </Dd> </Dl> <Dd> ε = r max − r min r max + r min . (\ displaystyle \ varepsilon = (\ frac (r_ (\ max) - r_ (\ min)) (r_ (\ max) + r_ (\ min))).) </Dd> <P> The area of the ellipse is </P> <Dl> <Dd> A = π a b . (\ displaystyle A = \ pi ab \, .) </Dd> </Dl>

Who proposed that planets orbit the sun in circular orbits