Ex 9.1

Chapter 9 Class 10 Some Applications of Trigonometry
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### Transcript

Ex 9.1 , 9 The angle of elevation of the top of a building from the foot of the tower is 30 and the angle of elevation of the top of the tower from the foot of the building is 60 . If the tower is 50 m high, find the height of the building. Let building be AB & tower be CD Given Height of the tower = 50 m Hence, CD = 50m Angle of elevation of top of building from foot of tower = 30 Hence, ACB = 30 Angle of elevation of top of tower from foot of building = 60 Hence, DBC = 60 We need to find height of building i.e. AB Since building & tower are perpendicular to ground ABC = 90 & DCB = 90 Similarly, In a right angle triangle ABC, tan C = ( " " )/( " " ) tan 30 = (" " )/ (" " 1)/ 3 = (" " )/((" " 50)/ 3) (" " 1)/ 3 = AB 3/50 (" " 1)/ 3 50/ 3 = AB AB = (" " 1)/ 3 50/ 3 AB = (" " 50)/3 m Hence, height of building = (" " 50)/3 m

#### Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.