6. Take any point $P$ on the line $x=3$, draw two tangents from point $P$ to the circle $x^{2}+(y-2)^{2}=4$, the points of tangency are $A, B$, then the line $A B$ passes through a fixed point, the coordinates of this fixed point are $\qquad$ .
$\left(\frac{4}{3}, 2\right)$