Ellipse
3.0 Important terms
3.0 Important terms
1. Centre: It is the point of the ellipse which bisects all the chords passing through it. As shown in figure $3$, $C$ is the centre of the ellipse.
2. Foci: $S$ and $S'$ be the two foci of the ellipse and their coordinates are $(ae,0)$ and $(-ae,0)$.
3. Directrices: The two lines shown in figure $3$ with equations $x = \frac{a}{e}$ and $x = - \frac{a}{e}$ are the two directrices of the ellipse.
4. Axes: The lines $AA'$ and $BB'$ are the major and minor axes of the ellipse.
5. Latus Rectum: The lines drawn perpendicular to the major axis $AA'$ and passing through the foci $S$ ans $S'$ are the latus rectum of ellipse. In figure $3$, $LL'$ and ${L_1}{L_1}'$ are the two latus rectum of the ellipse and the length of latus rectum is $\frac{{2{b^2}}}{a}$.
6. Focal Chord: A chord of the ellipse pasing through its focus is called a focal chord.
7. Vertices: The points where the ellipse meets its major axis are the vertices. As shown in figure $3$, the vertices are $A(a,0)$ and $A'(-a,0)$.
