Ellipse Construction

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Ellipse Construction

The long axis of an ellipse is the major axis.

The short axes is the minor axis. The foci E

and F are found by striking arcs with the

radius equal to half the major axis with the

center at the end of the minor axis.

Another method is to draw a semicircle

with the major axis as diameter then draw

G-H parallel to the major axis and G-E and

H-F are parallel to the minor axis as shown.

An Ellipse may also be generated by a point

moving so that the sum of its distances

from two points (the foci) is constant and

equal to the major axis. For example, an

ellipse may be constructed by placing a

looped string around the foci E and F and

around C, one end of the minor axis and

moving the pencil point P along its

maximum orbit while the string is kept taut.