Posts tagged 'euclid-vi-3'

F.27 Harmonic Mean

If C and D are harmonic conjugates with respect to segment AB (so |AC|/|CB| = |AD|/|BD|), then the length |CD| is the harmonic mean of |BD| and |AD|: |CD| = 2 |BD| |AD| / (|BD| + |AD|) = r (gamma + 1/gamma).