Example 4 - From a point P on the ground angle of elevation - Examples

  1. Chapter 9 Class 10 Some Applications of Trigonometry
  2. Serial order wise

Transcript

Example 4 From a point P on the ground the angle of elevation of the top of a 10 m tall building is 30 . A flag is hoisted at the top of the building and the angle of elevation of the top of the flagstaff from P is 45 . Find the length of the flagstaff and the distance of the building from the point P. (You may take 3 = 1.732)? Given Height of building = 10 metre. So, BA = 10m Angle of elevation from point P to the top of the building = 30 So, BPA = 30 Angle of elevation from point P to the top of flag = 45 So, DPA = 45 We have to find out the length of the flag i.e. DB. And, distance of the building from the P i.e. PA Since building is vertical to ground BAP = 90 In right angle triangle BAP, tan P = ( " P " )/( " " ) tan 30 = (" " )/ 1/ 3 = (" " 10)/ 1 PA = 10 3 PA = 10 3 metre Hence, Distance of the building from point, P = 10 3 Similarly, In right angle triangle DPA, tan P = ( " " )/( " " ) tan 45 = / 1 = / 1 = ( + )/ PA = DB + BA 10 3 = DB + 10 DB = 10 3 10 DB = 10 ( 3 1)metre Hence, length of the flagstaff = DB = 10 ( 3 - 1)metre

About the Author

Davneet Singh's photo - Teacher, Computer Engineer, Marketer
Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 8 years. He provides courses for Maths and Science at Teachoo. You can check his NCERT Solutions from Class 6 to 12.