Question

Find the length of sub -tangent of $y^2=12x$ at $(12,12)$

• A. $24$
• B. $32$
• C. $8$
• D. None of these

Answer 1

Answer: (A)

$24$

$y^2=12x$

$\therefore \frac{dx}{dy}=\frac{y}{6}$

Length of subtangent $=\left|y\right(\frac{dx}{dy}\left)\right|$

$=\left|\frac{y^2}{6}\right|$

So, the length of subtangent at $(12,12)=\left|\frac{{12}^2}{6}\right|=24$ units

So, the answer is option (A).