Online Geometry Problems

Online Geometry Problem 757: Equilateral Triangle, Circumcircle, Chords, a Half of Harmonic Mean. Level: High School, College, Mathematics Education

The figure shows an equilateral triangle ABC with circumcircle O. A chord CD meets AB at E. If AD = b and BD = c, prove that DE is half the harmonic mean of b and c or Formula to prove.
 

Equilateral triangle, Circumcircle, Harmonic Mean
 

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