Let K be the position of the kite, AK be the string and AB be the ground.
The height of the kite BK = 60 m
Let, length of the string AK = x m
In △ABK, sin60° = BK/AK
→√3/2 = 60/x
→x = 120/√3
→x = 120√3/√3√3
→x = 120√3/3
→x = 40√3
Hence, length of the string is 40√3 m.