Sat February 11, 2012 By: Apurv Palekar

A bird was flying in a line parallel to ground from north to south at a height of 200m.Tom standing in the middle of the field first he observed bird in north at an angle of 30degrees.After 3 minutes he observed it in south at an angle of 45degrees.Find speed of bird in km/hr(root3=1.73)

Expert Reply
Sat February 11, 2012
Let x be the distance covered by the bird to the left of boy
So 200/x = tan30 =1/root3
x = 200root3
Similarly let y be the distance travelled by the bird in the right of the boy
200/y = tan45 =1 , y =200
Speed  = (x+y)/180 = 200(root3 + 1)/1800 = (root(3) + 1)/9 = 2.73/9 = 0.303 m/s
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