# NCERT Mathematics Class 10 Exemplar Ch 8 Introduction to Trigonometry and Its Applications Part 2

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EXERCISE 8.2

1.

2. The value of the expression is positive.

3. The value of the expression negative.

4.

5. If then

6.

7. If the length of the shadow of a tower is increasing, then the angle of elevation of the sun is also increasing.

8. If a man standing on a platform 3 metres above the surface of a lake observes a cloud and its reflection in the lake, then the angle of elevation of the cloud is equal to the angle of depression of its reflection.

9. The value of can be , where a is a positive number, and .

10. , where a and b are two distinct numbers such that .

11. The angle of elevation of the top of a tower is 30°. If the height of the tower is doubled, then the angle of elevation of its top will also be doubled.

12. If the height of a tower and the distance of the point of observation from its foot, both, are increased by 10%, then the angle of elevation of its top remains unchanged.