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 re: Two solutions by Charlie)

I agree that in an acute triangle the central angles would sum to 360°. The 2-3-4 triangle, however, is obtuse.  

Posted by Jer on 2015-12-06 20:04:43