Standard equation
The standard form of an ellipse in Cartesian coordinates assumes that the origin is the center of the … 展开

Each of the two lines parallel to the minor axis, and at a distance of $${\textstyle d={\frac {a^{2}}{c}}={\frac {a}{e}}}$$ from it, is called a directrix of the … 展开

For the ellipse $${\displaystyle {\tfrac {x^{2}}{a^{2}}}+{\tfrac {y^{2}}{b^{2}}}=1}$$ the intersection points of orthogonal tangents lie on the circle $${\displaystyle x^{2}+y^{2}=a^{2}+b^{2}}$$ 展开

Standard parametric representation
Using trigonometric functions, a parametric representation of the standard ellipse 展开

An ellipse possesses the following property:
The normal at a point $${\displaystyle P}$$ bisects the angle between the lines
Proof 展开

Definition of conjugate diameters
A circle has the following property:
The midpoints of parallel chords lie on a diameter.
An affine transformation … 展开

Ellipses appear in descriptive geometry as images (parallel or central projection) of circles. There exist various tools to draw an ellipse. Computers provide the fastest and most accurate method … 展开