A boy standing in the middle of a field, observes a flying bird in the north at an angle of elevation fo 30 degree. and after 2 min, he observes the same bird in the south at an angle of elevation o f60 degree. If the bird flies all along in a straight line at a height of 50root3 m, then its speed in km/h is
A boy standing in the middle of a field, observes a flying bird in the north at an angle of elevation fo 30 degree. and after 2 min, he observes the same bird in the south at an angle of elevation o f60 degree. If the bird flies all along in a straight line at a height of 50root3 m, then its speed in km/h is