Mathematics - Circle Question with Solution | TestHub

$C_1,C_2$ are unit circles with centres $P=(0,0)$ and $Q=(1,0)$. The unit circle $C_3$ passes through $P,Q$ and has centre $R$ above the $x$-axis, so $R=(1/2,\sqrt{3}/2)$. The length of the common chord of the circles with $PQ$ and $PR$ as diameters is