An aeroplane flying horizontally at a height of 1.5 km above the ground is observed at a certain point on the earth to subtend an angle 60°. After 15 second its angle of elevation is observed to be 30°. Calculate the speed of aeroplane in Km/h.

A 1.2m tall girl spots a balloon moving with the wind in a horizontal line at a height of 88.2 m from the ground.The angle of elevation of the balloon from the eyes of the girl at any instant is 60^@ .After some time,the angle of elevation reduces to 30^@ (see Fig 9.13),Find the distance travelled by the balloon during the interval..

An aircraft is flying at a height of 3400 m above the ground. If the angle subtended at a ground observation point by the aircraft positions 10.0 s apart is 30^@ what is the speed of the aircraft?

An aeroplane when flying at a height of 3125mfrom the ground passes vertically below another plane at an instant when the angles of elevation of the two planes from the same point on the ground are 30° and 60° respectively. Find the distance between the two planes at the instant.

A man standing on the deck of a ship which is 10 m above the water level, observes the angle of elevation of the top of a hill as 60° and angle of depression of the base of a hill as 30°. Calculate the distance of the hill from the ship and the height of the hill.

A vertical post of height 5sqrt3 m above the horizontal ground casts a shadow of length 15 m on the ground.Find the angle of elevation of the sun.

The angle of elevation of a jet plane from a point P on the ground is 60°.After a flight of 15 second the angle of elevation changes to 30°. If the jet plane is flying at a constant height of 1500sqrt3 ,find the speed of the jet plane in km/ hr.

A fighter plane flying horizontally at an altitude of .1.5 km with speed 720 km/h passes directly overhead an anti-aircraft gun. At what angle from the vertical should the gun be fired for the shell with muzzle speed 600 m s^-1 to hit the plane? At what minimum altitude should the pilot fly the plane to avoid being hit? (Take g = 10 m s^-2) .

The angle of elevation of an aeroplane from a point A on the ground is 60^@ . After a flight' of 30 seconds, the angle of elevation changes to 30^@ . If the plane is flying at a constant height of 3600sqrt3 m , find the speed of the plane in km/hour.

A man is standing on the deck of a ship which is 25m above water level. He observes the angles of elevation of the top of a lighthouse as 60° and the angle of depression of the base of light house as 45°.Calculate the height of the light house.

The angle of elevation of a temple is found to be 30^@ as seen from a place.By advancing 50m towards the temple the angle of its elevation is observed to be 45^@ .Find the height of the temple.