This may be basic to some of you, but excuse my inexperience with comp. geometry:
Given a set of $n$ circles with centers $(x_i, y_i)$ for $1 \leq i \leq n$ and each having radii $r$. Also given a rectangle. All objects are on a plane. How to verify that every point inside the rectangle (including its edges) is fully covered by the circles. That is, each point in the rectangle lay on at least one of the circles.
Anyone have hints ? I am currently trying with voronoi diagrams.