Figure: An ellipse. The foci are indicated by the points
marked F. The dashed line indicates the sum of the distances between
the foci and a point on the ellipse.
The length R is the semimajor axis.
A geometric figure generated by keeping the sum of the distance from two fixed points (the foci) constant.
Figure: An ellipse. The foci are indicated by the points
marked F. The dashed line indicates the sum of the distances between
the foci and a point on the ellipse.
The length R is the semimajor axis.