area of ABS = area of CDS = area of EFS
Kepler's 3 Laws of Planetary Motion
First Law: The orbit of each planet is the shape of an ellipse with the sun located at one focus (Astronomia nova... (The New Astronomy...), 1609).
Second Law: In any equal time interval, a line from a planet to the sun will sweep out equal areas (Astronomia nova..., 1609).
area of ABS = area of CDS = area of EFS
Third Law: The ratio of the cube of the average distance of a planet from the sun to the square of the time required for it to make a revolution around the sun is equal to the same ratio for any other planet (Harmonice Mundi (The Harmony of the World), 1619).
D3Earth/T2Earth = D3Mars/T2Mars = D3Saturn/T2Saturn = ... or D3/T2 = K (constant)