1)

The equation of the chord of the hyperbola 25x2 - 16y2 = 400, that is bisected at point (5,3) is:


A) 135 x - 48y = 481

B) 125x - 48y = 481

C) 125 x - 4y = 48

D) None of these

Answer:

Option B

Explanation:

The equation of the chord, having mid-point  as (x1, y1), of the hyperbola

$\frac{x^{2}}{a^{2}}-\frac{y^{2}}{b^{2}} = 1$ is given by T = S....(i)

Where, T = $\frac{xx_{1}}{a^{2}}-\frac{yy_{1}}{b^{2}}-1$

and S= $\frac{x_{1}^{2}}{a^{2}}-\frac{y_{1}^{2}}{b^{2}}-1$

According to the question,  (x1, y1) = (5, 3) and a2 = 16 b2 = 25

and 25x2 - 16y2 = 400,

$\frac{x^{2}}{16}-\frac{y^{2}}{25} =1$

$\frac{5x}{16}-\frac{3y}{25} =\frac{25}{16}-\frac{9}{25}$

                                                             [using (i)]

125x - 48y = 625 - 144 = 125x - 48y = 481