Equation of a Focal Chord Through a Focus

Equation of a Focal Chord Through a Focus

For:

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

a line through $$S_2(c,0)$$ with slope $$m$$ is:

$$y=m(x-c)$$

Its intersections with the ellipse give the endpoints of the focal chord.

Usage

- Used when the direction of the focal chord is specified.