Two mirror walls are placed to form an angle of measure . There is a candle inside the angle. How many reflections of the candle can an observer see?
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Two mirror walls are placed to form an angle of measure $\alpha$. There is a candle inside the angle. How many reflections of the candle can an observer see?
Izvor: Međunarodna matematička olimpijada, shortlist 1966
Školjka 
. There is a candle inside the angle. How many reflections of the candle can an observer see?