Last updated at May 29, 2018 by Teachoo

Transcript

Ex 9.1 , 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. Let the man & tower height be AD Given that man sees car first at an angle of depression of 30 So, PAB = 30 After 6 seconds, the man sees car at an angle of depression of 60 So, PAC = 60 Now, tower is vertical, So, ADB = 90 Also, From (1) & (2) 3 CD = / 3 3 ( 3 CD) = BD 3CD = BD 3CD = BC + CD 3CD CD = BC 2CD = BC CD = /2 Given that Time taken to cover BC = 6 seconds Time taken to cover /2 = 6/2 seconds = 3 seconds Time taken to cover CD = 3 seconds

Questions easy to difficult

Angle of Elevation and Angle of Depression

Angle of Depression from point A to point B is same as Angle of Elevation from point B to point A

How to find Height when angle of elevation is given?

How to find Distance when angle of depression is given?

Example 1

EX 9.1, 4

EX 9.1, 5

EX 9.1, 3 Important

EX 9.1, 2 Important

Ex 9.1, 7

Example 4

Example 2 Important

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Example 5 Important

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Example 7 Important

Example 3 Important

Ex 9.1, 6 Important

EX 9.1, 9 Important

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Example 6 Important

Ex 9.1, 13 Important

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Ex 9.1, 14 Important

Ex 9.1, 15 Important You are here

EX 9.1, 1

About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 10 years. He provides courses for Maths and Science at Teachoo.