Question

Find the length of sub -tangent of $\frac{x^2}{9}-\frac{y^2}{9}=1$ at $(4,4)$

• A. $\frac{7}{4}$
• B. $\frac{17}{4}$
• C. $\frac{27}{4}$
• D. None of these

Answer 1

The correct option is A $\frac{7}{4}$

Length of sub-tangent $=x_1-\frac{a^2}{x_1}$

simply put $x_1=4$ and $a^2=9$

Length of sub-tangent $=4-\frac{9}{4}$

$=\frac{7}{4}$