Two circles intersect at two points, $P$ and $Q$. The equations of the two circles are $x^2 + y^2 = 1$ and $(x - 1)^2 + (y - 1)^2 = 1$. Find the slope of line $PQ$.
Center of first circle = (0,0) = P
Center of second circle = (1,1) = Q
Can you take it from here ???