The angle of elevation of an aeroplane from a point on the ground is 45°. After flying for 15 seconds, the elevation changes to 30°. If the aeroplane is flying at a height of 2500 metres, then the speed of the aeroplane in km/hr. is
1. A boat is moving away from an observation tower. It makes an angle of depression of 60° with an observer's eye when at a distance of 50m from the tower. After 8 sec., the angle of depression becomes 30°. By assuming that it is running in still water, the approximate speed of the boat is
2. The upper part of a tree broke at a certain height makes an angle of 60 ° with the ground at a distance of 10 m. from its feet. The original height of the tree was
3. The angle of elevation of a ladder leaning against a wall is 60 deg and the foot of the ladder is 4.6 m away from the wall. The length of the ladder is
4. From the top of a 20 m high building, the angle of elevation of the top of a tower is 60° and the angle of depression of it's foot is at 45°, then the height of the tower is (?3=1.732)
5. Two persons are on either side of a temple, 75 m high, observe the angle of elevation of the top of the temple to be 30 and 60 deg respectively. The distance between the persons is
7. Two men are on opposite sides of a tower. They measure the angles of elevation of the top of the tower as 30 ? and 45 ? respectively. If the height of the tower is 50 m, the distance between the two men is (Take ?3 = 1.73)
8. A 25m long ladder is rested on a wall. The foot of the ladder is 7m away from the wall. If the end of the ladder (resting on the wall) slides down 4m, then how far will its foot move away?
9. The angles of elevation of top and bottom of a flag kept on a flag post from 30 metres distance, are 45 and 30 deg respectively. Height of the flag is [taking ?3 = 1.732]
10. A pilot in an aeroplane at an altitude of 200 m observes two points lying on either side of a river. If the angles of depression of the two points be 45° and 60°, then the width of the river is