<Li> The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit . </Li>
<Li> The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit . </Li>
the square of the period of a planet is equal to what cubed
the square of the period of a planet is equal to what cubed
semi-major axis
semi-major axis