Distance Between the Foci

Distance Between the Foci

$$S_1S_2=2c$$

Usage

- Used to calculate the separation between the two foci.

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## 13. Relation Between Eccentricity and Semi-Axes

$$e^2=1+\frac{b^2}{a^2}$$

Usage

- Used when $$a$$, $$b$$ or $$e$$ is known and another parameter needs to be determined.