MathDB

3. Let

k

and

K

be concentric circles on the plane, and let

k

be contained inside

K

. Assume that

k

is covered by a finite system of convex angular domains with vertices on

K

. Prove that the sum of the angles of the domains is not less than the angle under which

k

can be seen from a point of

K

. (G.38) [Zs.. Páles]

Problem Statement