A planet of mass `m` moves around the sun of mass M in an elliptical orbit. The maximum and minimum distance of the planet from the sun are `r_(1) and r_(2)` respectively. The time period of the planet is proportional to

Explanation

Here semimajor axis of the eliptical orbit of the planet around the sun is
`r=((r_(1)+r_(2)))/2`
Therefore `T^(2)prop((r_(1)+r_(2))/2)^(3)`
or `Tprop((r_(1)+r_(2))/2)^(3/2)`
or `Tprop(r_(1)+r_(2))^(3/2)`