4. From the top of a tower 60 mts high the angle of depression of the top and bottom of a pole are observed to be 45° and 60° respectively. If the pole and tower stand on the same plane, the height of the pole in meters is
5. A Navy captain going away from a lighthouse at the speed of 4[(?3) ? 1] m/s. He observes that it takes him 1 minute to change the angle of elevation of the top of the lighthouse from 60 to 45 deg. What is the height (in metres) of the lighthouse?
6. 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. 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)
8. 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
9. 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
10. 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