Pick two points at random on a circle and draw the chord connecting them.

Pick two more points and connect them with a second chord.

What is the probability that these chords intersect?

(In reply to re: solution, maybe by Charlie)

In fact, this solution remains the same even if the figure had been a square rather than a circle, as the probability is zero that any chosen point is a corner.

Posted by Charlie on 2009-05-12 11:10:59