**Applications of Trigonometry Heights and Distances Chapter 9 Exercise 9.1 Question 15**

**15. **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 30, 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 60. Find the time taken by the car to reach the foot of the tower from this point.

**Solution:**

It is given that car travels from point D to point C in 6 seconds.

In , we have

**(1)**

In , we have

**(2)**

From **(1) and (2)**, we can say that

**Therefore, length of CD is twice as length of BC.**

Car is traveling at uniform speed and it is given that car takes 6 seconds to move from point D to C.** Therefore, the time required to move from point C to B would be 3 seconds. **