A circular park of radius 20 cm is situated in a colony. Three boys Ankur, Syed and David are sitting at equal distance on its boundary each having a tou telephone in his hand to taks to each ohter. Finf the length of the string of each phone.

  
Put the parts in order to form a sentence. When you think your answer is correct, click on "Check" to check your answer. If you get stuck, click on "Hint" to find out the next correct part.