An observer at an anti air craft post A identifies an enemy aircraft due East of his post at an angle of elevation of `60^@`. At the same instant a detection post D 4kms south of A reports the aircraft at an elevation of `30^@`. Calculate the altitude at which the plane is flying.

The angle of elevation of an aeroplane from a point P on the ground is 60^(@) . After 12 seconds from the same point P, the angle of elevation of the same plane changes to 30^(@) . If the plane is flying horizontally at a speed of 600sqrt3 km/h, find the height at which the plane is flying.

Mohit, standing in the midst of a field, observes a flying birds in his north at an anlge of elevation of 30^@ and after 2 minutes he observes the birds in his south at an angle of elevation of 60^@ . If the bird flies in a straight line all along at a height of 50sqrt3 metres then find its speed in km//hr .

A man standing in the midst of a field observes, a flying bird in his north at an angle of elevation of 30^@ and after 2.5 minutes he observes the bird in his south at an angle of elevation of 60^@ . If the bird flies in a straight line all along at a height of 60sqrt3 metres, what is its speed?

Narayan, standing in the midst of a field, observes a flying bird in his north at an angle of elevation of 30^@ and aft er 21 minutes he observes the bird in his south at an angle of elevation of 60^@ . If the bird flies in a s traight line all a height of 50sqrt3 metres, then find its speed in metre per minuts.

Monu standing in the midst of a field, observes a flying bird in his north at an angle of elevation of 30^(@) and after 2 minutes he observer the bird in his south at an angle of elevation of 60^(@) . If the bird flies in a straight line all along at a height of 50sqrt(3) metres, find its speed in kilometre per hour.

A boy standing in the middle of a field, observes a flying bird in the north at an angle of elevation of 30^(@) and after 2 minutes, he observes the same bird in the south at an angle of elevation of 60^(@) . If the bird flies all along in a straight line at a height of 50sqrt(3) m, then its speed in km/h is

The angle of elevation of an aircraft from a point on horizontal ground is found to be 30^(@) . The angle of elevation of same aircraft after 24 seconds which is moving horizontally to the ground is found to be 60^(@) . If the height of the aircraft from the ground is 3600 sqrt(3) metres, find the velocity of the aircraft.

To a person standing at the middle point of the horizontal straight line joining the feet of two vertical posts of the same height, the angle of elevation of the top of each post appears to be 30^@ . After walking 40metres towards one of them , the person observes that the angle of elevation of the top of the same post has changed to 60^@ . Find the distance between the two posts.