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Probability 7.0/10

Bertrand's Chord

A chord of a circle is drawn by choosing its two endpoints independently and uniformly on the circumference. What is the probability the chord is longer than a side of the inscribed equilateral triangle? Express as a fraction.

Related problems & prerequisites

Worth solving first

Source: Bertrand's paradox, from Joseph Bertrand, 'Calcul des probabilites' (1889). Statement written for AxiomIQ.