Question

The Equation of chord of contact of $\frac{x^2}{25}+\frac{y^2}{16}=1is4x+5y-20=0$ Find the point from which the tangents are drawn

• A. (4, 5)
• B. (6, 5)
• C. (4, 6)
• D. (5, 4)

Answer 1

The correct option is D

(5, 4)

Let the point be (x_1,y_1).
The equation of chord of contact is given by T = 0

$\Rightarrow \frac{x{x}_1}{25}+\frac{y{y}_1}{16}=1$ .....(1)

This is given as 4x + 5y - 20 = 0

$Or\frac{x}{5}+y4=1$ ....(2)

$\Rightarrow$ Comparing (1) and (2)

$\Rightarrow \frac{x_1}{25}=\frac{1}{5}and\frac{y_1}{16}=\frac{1}{4}$

$\Rightarrow (x_1,y_1)=(5,4)$