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?

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.

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 .

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.

A man standing on a railway bridge 5sqrt3 meters high, observes the engine of a train at an angle of depression 30^@ . But after 2 seconds, he observes the engine at an angle of depression 45^@ on the other side of the bridge. Find the speed of the train.

The angle of elevation of a jet plane from a point on the ground is 60^@ . After a flight of 15 seconds, the angle of elevations changed to 30^@ . If the jet plane is flying horizontally at a constant height of 1500sqrt3 metres, find the speed of the jet plane.

A man, standing on the bank of a river observes that the angle of elevation of the top of a tree just on the opposite bank is 60^@ But the angle off elevations is 30^@ from a point at a distance y metres from the bank. Show that the height of tree h= sqrt(3y)/2.

A man standing on a railway overbirdge of 5sqrt3 m height observed the engine of the train from one side of the bridge at an angle of depression of 30^@ . But just after 2 seconds, he observed the engine at an angle of depression of 45^@ from the other side of the bridge. Find the speed of the train.

From a point on the horizontal line through the foot of a chimney the angle of elevation of the top of the chimney is 30^@ . and the angle of elevation is 60^@ at a point on the same straight line 50 metres nearer to the chimney. What is the height of the chimney?

The angle of elevation of a jet plane from a point A on the ground is 60^(@) . After a flight of 15 seconds, the angle of elevation changes to 30^(@) . If the jet plane is flying at a constant height of 1500sqrt3 meter, find the speed of the jet plane. (sqrt3 = 1.732)

A round balloon of radius 10m subtends an angle of 60^@ at the eye of the observer while the angle of elevation of its centre is 30^@ . Which of the following is the height of the centre of the balloon?