A one-rupee coin is placed on a plain paper. How many coins of the same size can be placed round it so that each one touches the centre and adjacent coins ?

Solution (By Examveda Team)

When 3 congruent circles touch each other externally, the triangle formed with their centers is an equilateral triangle. Hence when a circle is surrounded by identical circles, centers of two consecutive circles make an angle of 60° with the central circle. Thus, six identical circles a surround a circle of equal radius.