I want answers to these questins immediatly.[I do not want the questions to be altered.]

Can anyone plz answer them correctly

1. the angle of depression of the top of a tower as observed from a point on the ground is "alpha" and on moving 'a' metres towards the tower, the angle of elevation is 'beta'. prove that the height of the tower is a*tan'alpha'tan'beta' / tan'beta' - tan'alpha'.

2. A man on the top of a vertical tower observes a car moving at a uniform speed coming directly towards it. If it takes 12 minutes for the angle of depression to change from 30 degrees to 45 degrees, how soon after this will the car reach the tower?

3. A boy standing on a horizontal plane finds a bird flying at a distance of 100 m from him at an elevationof 30 degrees. A girl standing on the roof of a 20 metre high building, finds the angle of elevation of the same bird to be 45 degrees. both the boy and the girl are on opposite sides of the bird. FInd the distance of the bird from the girl.

4. A person standing on the bank of a river observes that the angle of elevation of the top of a tree standing on the opposite bank is 60 degrees. When he moves 40 m away from the bank, he finds the angle of elevation to be 30 degrees. Find the height of the tree and the width of the river.

5. the angle of elevation of a jet fighter from a point A on the ground is 60 degrees. After a flight of 15 seconds, the angle of elevation changes to be 30 degrees. If the jet is flying at a speed of 720 km/hr. find the constant height taking root 3 as 1.732.

6.The angle of elevation of an aeroplane from a point A on the ground is 60 degrees. After a flight of 30 seconds the angle of elevation changes to 30 degrees. If the plane is flying at a constant height of 3600root3 m. Find the speed in km/hr of the plane.

7. An aeroplane when 3000 m high, passes vertically above another aeroplane at an instant, when the angle of elevation of the two aeroplanes from the same point on the ground are 60 degrees and 45 degrees respectively. Find the vertical distance b/w the aeroplanes.

8. A straight highway leads to the foot of the tower. A man standing on top of the tower observes a car at an angle of depression of 30 degrees, which is approachingthe foot of the tower with a uniform speed ,6 seconds later the angle of depression of the car is found to be 60 degrees. FInd the time taken by the car to reach the foot of the tower from this point.

9.The angle of elevation of the top of a building from the foot of a tower is 30 degrees and the angle of elevation of the top of the tower from the foot of the building is 60 degrees. I the tower is 50 m high. find the height of the building.