[Trigonometry] HnD Type #2: Broken Trees and Telegraph Poles: Finding original height

Aptitude6 Comments

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  1. Introduction: Broken trees and poles
  2. Approach
  3. Mock Questions

Introduction

Trigonometry –>Height and Distance(HnD)–> Five types of Questions.
2nd type of question is “Broken trees and telephone poles”. Here are the examples (both of them solved in the video)

  1. Because of storm, a tree is broken from a point above the ground. The top of the tree meets ground @distance that is 8 root 3 away from its foot. Angle of elevation is 30 degree. Find original height of this tree.
  2. A telegraph pole is broken during storm. Its top is stuck at the ground at an angle of 30 degrees, and @distance of 30 m away from the bottom of the pole. Find original height of this pole

Approach

  1. Original height of a tree or telephone = length of broken down part + length of leftover part.
  2. This is basically one building-one angle type question. Only different is “broken down part=hypotenuse”.
  3. So first make TAN equation, you’ll find the height of opposite side =leftover part.
  4. Then make equation for SIN and you’ll find length of hypotenuse =broken down part. (or use Pythagoras)
  5. Then add the lengths of opposite side + hypotenuse= you get the original height.

Check the following video to see how ^this approach exactly works. And after watching the video, solve the mock questions given at the bottom of this article.

If the video is not visible, check it directly on my youtube channel youtube.com/user/TheMrunalPatel

Mock Questions

  1. A tree breaks down due to storm and its top touches the ground and makes an angle of 30°. If the top of that tree touches the ground 15 m away from the bottom then find the height of this tree.
  2. A telephone pole is broken during storm. Its top is stuck at the ground at an angle of 30 degrees, and @ distance of 90 m away from the bottom of the pole. Find original height of this pole

Answer

  1. 15 ROOT 3 OR 25.95
  2. 90 root 3 OR approx. 156m

For more [Aptitude] related content, visit the Archive on Mrunal.org/aptitude

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So far 6 Comments posted

  1. surabhi

    Sir please explain us the new format of civil services exam 2013 (mains) recently notified by the DoPT.
    Thanks

  2. Prasanta math

    If you kindly suggest & explain geometry for ssc then I will be thankful to you.

  3. anuradha

    sir kindly help in Geometry too

  4. kartik

    Sir,
    you really have an awesome way of teaching trigonometry and i request you to please come up with videos of geometry as well as it will help aspirants to clear the exams in an easy way . I wish you best of luck for your future , you are really doing a great job , may god help you in prospering in all fields of your life.

    With Regards,
    Kartik Maharishi

  5. eldho

    sir,
    i think ans of the mock questions are 15(root3)+30 and 90(root3)+180…

    1. Mudasir

      @eldho
      tan 30=a/15
      1/root 3=a/15
      a=5root3
      b^2=5root3^2+15^2
      b=10root3
      height=a+b
      =15root3

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