. A straight highway leads to the foot of a tower


A man standing at the top of the tower observes a car at an angle of depression of  30º , which is approaching the foot of the tower with a uniform speed. Six seconds later, the angle of depression of the car is found to be  60º. Find the time taken by the car to reach the foot of the tower from this point.

 

Best Answer

Explanation:

straight highway

Let us assume that the length of the tower = AB = h m

Let the initial position of the car = D

Let the final position of the car = C

Then the distance from the car to the foot of the tower = BC

straight highway1

straight highway2

 

We observe from the equation above that the distance BC = ½ of CD

Therefore, the time taken will also be half.

According to question, the car travels the distance CD in 6 seconds

Then the car will travel the distance BC in 6/2 = 3 seconds.

Final Answer: 

The time taken by the car to reach the foot of the tower from this point= 3 seconds.

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