(131) 7

Part of 1986 Tournament Of Towns

Problems(1)

TOT 131 1986 Autumn S7 21 points on a circle, angle of arc <=120

Source:

On the circumference of a circle are

21

points. Prove that among the arcs which join any two of these points, at least

100

of them must subtend an angle at the centre of the circle not exceeding

120^o

.
( A . F . Sidorenko)

combinatoricscombinatorial geometryarcanglespointscircle