10. Tangents are drawn from any point on the hyperbola $x ^ { 2 } / 9 - y ^ { 2 } / 4 = 1$ to the circle $x ^ { 2 } + y ^ { 2 } = 9$. Find the locus of mid-point of the chord of contact.
A plane at a distance of 1 unit from the origin cuts the coordinate axes at $A , B$ and $C$. If the centroid $D ( x , y , z )$ of the triangle $A B C$ satisfies the relation $\frac { 1 } { x ^ { 2 } } + \frac { 1 } { y ^ { 2 } } + \frac { 1 } { z ^ { 2 } } = k$, the value of $k$ is
10. Tangents are drawn from any point on the hyperbola $x ^ { 2 } / 9 - y ^ { 2 } / 4 = 1$ to the circle $x ^ { 2 } + y ^ { 2 } = 9$. Find the locus of mid-point of the chord of contact.\\