MathDB

3

Part of 2007 Greece National Olympiad

Problems(1)

maximum circles

Source: Greek MO 2007

3/5/2007
In a circular ring with radii 11r11r and 9r9r, we put circles of radius rr which are tangent to the boundary circles and do not overlap. Determine the maximum number of circles that can be put this way. (You may use that 9.94<99<9.959.94<\sqrt{99}<9.95)