Last updated at Dec. 8, 2016 by Teachoo

Transcript

Ex 9.1 , 5 A kite is flying at a height of 60 m above the ground. The string attached to the kite is temporarily tied to a point on the ground. The inclination of the string with the ground is 60°. Find the length of the string, assuming that there is no slack in the string. Given that, Height at which kite is flying = 60 metre Hence, AB = 60 m Also, inclination of the string with the ground = 60° Hence, ∠ACB = 60° We have to find length of string, i.e., AC Here, AB is perpendicular to ground So, ∠ ABC = 90° In right triangle ABC sin C = (𝑆𝑖𝑑𝑒 𝑜𝑝𝑝𝑜𝑠𝑖𝑡𝑒 𝑡𝑜 𝑎𝑛𝑔𝑙𝑒" " 𝐶" " )/𝐻𝑦𝑝𝑜𝑡𝑒𝑛𝑢𝑠𝑒 sin C = 𝐴𝐵/𝐴𝐶 sin 60° = 60/AC √3/2 = 60/AC AC = 2/√3 × 60 AC = 120/√3 Multiplying √3 in both numerator and denominator AC = 120/√3 × √3/√3 AC = (120√3)/3 AC = 40√3 m Hence, Length of the string = AC = 40√3 metre

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, 1

EX 9.1, 3

EX 9.1, 2

EX 9.1, 5 You are here

Ex 9.1, 7

Example 2

Example 3

Example 4

EX 9.1, 8

Example 5

Ex 9.1, 6

EX 9.1, 9

Ex 9.1, 10

Ex 9.1, 11

Example 6 Important

Ex 9.1, 12

Ex 9.1, 13 Important

Ex 9.1, 16

Example 7

Ex 9.1, 14 Important

Ex 9.1, 15 Important

About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.