IIT-JEE 1998Question 391
$C_1$ and $C_2$ are two concentric circles, the radius of $C_2$ being twice that of $C_1$. From a point $P$ on $C_2$, tangents $PA$ and $PB$ are drawn to $C_1$. Prove that the centroid of the triangle $PAB$ lies on $C_1$.
Circle
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