I don't know but in school I learnt it in a different way. I mean in school the Kepler's third law was thought as if all the orbits were circular. But according to the definition its all elleptical, and in the school equation we won't add the planets mass, but here(adsbygoogle = window.adsbygoogle || []).push({});

http://en.wikipedia.org/wiki/Kepler's_third_law

The planet mass is also added.

So I am not sure what kind of equation I should use to solve sums?

Thanks

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# Kepler's third law

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