Question

Q. A boy, on the top of a 10 m high building is flying a kite, the string
making an angle of 45º with the horizontal. Another boy is flying
a kite from the ground. When the two kites meet, the angle of
elevation of this boy’s kite is 60º and the length of string the first
boy is using at that time is 42 m. Assuming that there is no slag
in the stings, find the length of string the second boy is using at
that time.​

Answer 1

Given A boy, on the top of a 10 m high building is flying a kite, the string

making an angle of 45º with the horizontal.  

length of string the first  boy is using at that time is 42 m

angle of  elevation of this boy’s kite is 60º  

To Find  : the length of string the second boy is using at  that time.​

Solution:

A boy, on the top of a 10 m high building is flying a kite,

the string  making an angle of 45º

length of string  = 42 m

Sin 45° =  h/42

=> 1/√2 = h/42

=> h = 21√2

Height from ground = 21√2 + 10 m

Sin 60°  = Height from ground  / length of string the second boy is using

=> √3 /2 =  (21√2 + 10) / L

=> L = (42√2 + 20) / √3

=> L  =  45.84 m

length of string the second boy is using   = 45.84 m

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