# The area of the triangle formed by the tangent at any point on the rectangular hyperbola $xy=72$ and its asymptotes is

$\begin{array}{1 1}(1)36&(2)18\\(3)72&(4)144\end{array}$

The equation of the given rectangular hyperbola is $xy=72$
$c^2=72$
Required area $= 2c^2 =144$
Hence 4 is the correct answer