From the top of a 100 m high tower a car is seen moving straight towards the foot of the tower. Its angle of depression changes from 30° to 60° in 12 minutes. At the same speed, the time it still needs to reach the foot of the tower is:

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Accepted Answer

6 minutes. The car's distances from the foot are 100·cot30° = 100√3 and 100·cot60° = 100/√3. It covers 100√3 − 100/√3 = 200/√3 m in 12 minutes, and 100/√3 m is left — exactly half of that, so it needs 6 more minutes.

From the top of a 100 m high tower a car is seen moving straight towards the foot of the tower. Its angle of depression changes from 30° to 60° in 12 minutes. At the same speed, the time it still needs to reach the foot of the tower is:

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