Pair of Tangents from a Point on the Major Axis

Pair of Tangents from a Point on the Major Axis

For:

$$P(x_1,0)$$

the pair of tangents to the ellipse is:

$$\left(\frac{xx_1}{a^2}-1\right)^2=\left(\frac{x_1^2}{a^2}-1\right)\left(\frac{x^2}{a^2}+\frac{y^2}{b^2}-1\right)$$

Usage

- Used when the combined equation of the two tangents from a point on the major axis is required.