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ASU 443 All Soviet Union MO 1987 r. heptagon 1/A_1A_5+1/A_1A_3=1/A_1A_7

Source:

August 7, 2019

Heptagongeometry

Problem Statement

Given a regular heptagon

A_1...A_7

. Prove that

\frac{1}{|A_1A_5|} + \frac{1}{|A_1A_3| }= \frac{1}{|A_1A_7|}