State Kepler's three laws.

Explanation

1 Law of Orbits : Each planet revolves moves around the Sun in an elliptical orbit with the Sun at one of the foci of the ellipse.
2 Law of area: The radial vector line joining the Sun to a planet sweeps equal areas in equal intervals of time.
3 Law of period: The square of the time period of revolution of a planet around the Sun in its elliptical orbit is directly proportional to the cube of the semi - major axis of the ellipse.
` T^(2) prop a^(3)`
`(T^(2))/(a^(3)) ` = constant