MathDB
5 congruent circles in a regular pentagon

Source: 2021 VWO Flanders MO p2

May 29, 2021
geometrypentagon

Problem Statement

Catherine lowers five matching wooden discs over bars placed on the vertices of a regular pentagon. Then she leaves five smaller congruent checkers these rods drop. Then she stretches a ribbon around the large discs and a second ribbon around the small discs. The first ribbon has a length of 5656 centimeters and the second one of 5050 centimeters. Catherine looks at her construction from above and sees an area demarcated by the two ribbons. What is the area of that area?
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