O is the center of a circle. AB, CD and EF are three parallel chords of this circle having respective lengths 2, 3 and 4.
It is known that ∠AOB = m, ∠COD = n and, ∠EOF = m+n, where m+n < 180^{o}
Determine cos m
(In reply to
Two solutions by Jer)
If you rotate the chords, how do you form a triangle when the ends don't meet? The central angles being m, n and m+n, the total of the central angles (and the arcs of the chords) is m + n + (m+n), or 2*(m+n). As m+n<180°, 2*(m+n)<360° and the arc ends, along with the chord ends, don't span the entire circumference.

Posted by Charlie
on 20151206 15:08:11 