32. SECTION -D- 5 Marks
A vertical tower stands on horizontal plane and is surmounted by a vertical flag-staff of height 6 m. At a point on the ground, angle of elevation of the bottom and top of the flag-staff are 30c and 45c respectively. Find the height of the tower. (Take . 3173 = )
33. A man in a boat rowing away from a light house 100 m high takes 2 minutes to change the angle of elevation of the top of the light house from 60c to 30c . Find the speed of the boat in metres per minute. .Use√3=1.732
34. Amit, standing on a horizontal plane, find a bird flying at a distance of 200 m from him at an elevation of 30c. Deepak standing on the roof of a 50 m high building, find the angle of elevation of the same bird to be 45c. Amit and Deepak are on opposite sides of the bird. Find the distance of the bird from Deepak.
35. Two poles of equal heights are standing opposite to each other on either side of the road which is 80 m wide. From a point P between them on the road, the angle of elevation of the top of a pole of a pole is 60c and the angle of depression from the top of the other pole of point P is .30c Find the heights of the poles and the distance of the point P is 30º from the poles.
36. Section E - Case based Question 4 Marks
Q1. Lakshaman Jhula is located 5 kilometers north-east of the city of Rishikesh in the Indian state of Uttarakhand. The bridge connects the villages of Tapovan to Jonk. Tapovan is in Tehri Garhwal district, on the west bank of the river, while Jonk is in Pauri Garhwal district, on the east bank. Lakshman Jhula is a pedestrian bridge also used by motorbikes. It is a landmark of Rishikesh. A group of Class X students visited Rishikesh in Uttarakhand on a trip. They observed from a point (P) on a river bridge that the angles of depression of opposite banks of the river are 60° and 30° respectively. The height of the bridge is about 18 meters from the river.
Based on the above information answer the following questions.
(i) Find the distance PA.
37. (ii) Find the distance PB
38. (iii) Find the width AB of the river.
39. Q2. A group of students of class X visited India Gate on an education trip. The teacher and students had interest in history as well. The teacher narrated that India Gate, official name Delhi Memorial, originally called All-India War Memorial, monumental sandstone arch in New Delhi, dedicated to the troops of British India who died in wars fought between 1914 and 1919. The teacher also said that India Gate, which is located at the eastern end of the Rajpath, is about 42 metres in height.
(i) What is the angle of elevation if they are standing at a distance of 42
m away from the monument?
40. (ii) They want to see the tower at an angle of 60°. So they want to know the distance where they should stand and hence the distance is
41. (iii) If the altitude of Sun is at 60° then the height of the vertical tower
that will cast a shadow of length 20 m, is
42. Q3. A boy is standing on the top of light house. He observed that boat P and boat Q are approaching to light house from opposite directions. He finds that angle of depression of boat P is 45° and angle of depression of boat Q is 30°. He also knows that height of the light house is 100 m.
Based on the above information, answer the following questions.
(i) Measure of angle ACD isEqual to