[填空题]
Consider the Voronoi diagram below with sites A, B, C a1n9; 9 ,n2/lf oxrs*um sdwziup*- bbfndcj,o z:xx;yyf ):7z rv D, and intersections E and F.
fy::vyjr zox 7x c)z;,
1.Determine the site closest to the coordinate (9,6).
2.Determine the coordinates of the centre of the largest empty circle.
3.Calculate the area of the largest empty circle. a ≈ $units^2$