A circular park of radius 20m is situated in a coloney. three boys ankur,syed and david are sitting at equal distance on its boundary each having a toy telephone in his hands to talk each other. find

a circular park of radius 20m is situated in a coloney. three boys ankur,syed and david are sitting at equal distance on its boundary each having a toy telephone in his hands to talk each other. find the length of the string of each phone