Find below the NCERT Exemplar problems and their solutions for Class 10 Mathematics Chapter, Introduction to Trigonometry and its Applications:

Exercise 8.2

Very Short Answer Type Questions (Q. No. 8-12)

Write whether True or False and justify your answer.

Question. 8 If a man standing on a platform 3m 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.

Solution. False

Let the observer stands on point P on a platform 3m above the surface of a lake. Also, let C be the cloud and C’ be its reflection in lake. Again, let height of the cloud from the surface of the platform be h and q₁ and q₂ be the angle of elevation and angle of deptression respectively of the cloud.

Question. 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.

Solution. False

Question. 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.

Solution. True

Case II: On increasing height of a tower and the distance of the point of observation from its foot, by 10%, we have:

Hence, the angle of elevation of the tower top remains unchanged.