Home/ Questions/Q 1611
Next
Answered
Jay Singh
  • 3
Asked: 2020-10-30T03:31:37+00:00 In:

If 3 cot A = 4, check whether 1- tan² A / 1+ tan² A= cos²A – sin² A or not.

  • 3

NCERT Solutions for Class 10 Maths Chapter 8
Important NCERT Questions
Introduction Trigonometry
NCERT Books for Session 2022-2023
CBSE Board and UP Board Others state Board
EXERCISE 8.1
Page No:181
Questions No:8

2020-2021cbsechapter 8class10introduction trigonometrymathematicsncert
Share

    2 Answers

    1. Best Answer
      If 3 cot A = 4, check whether 1- tan² A / 1+ tan² A= cos²A – sin² A or not.

      Given that: 3 cot A = 4
      ⇒ cot A = 4/3
      Let cot A = 4k/3k, where k is a real number.
      In △ABC, by Pythagoras theorem, we have
      AC² = BC²+AB²
      = (3k)²+(4k)²
      = 9k²+16k²
      = 25k²
      ⇒ AC = √(25k²) = 5k
      Therefore,
      (1-tan²A)/(1+tan²A) = (1-(3/4)²)/(1+(3/4)²) = (1-(9/16))/(1+(9/16)) = ((16-9)/16)/((16+9)/16) = 7/25
      and
      cos² A-sin²A = (4/5)²-(3/5)² = 16/25 – 9/25 = (16-9)/25 = 7/25
      Hence, (1-tan²A)/(1+tan²A) = cos²A-sin²A

      Video Solution of the above question is here🙌😃

      • 1

    2. Get Hindi Medium and English Medium NCERT Solution for Class 10 Maths to download.
      Please follow the link to visit website for first and second term exams solutions.
      https://www.tiwariacademy.com/ncert-solutions/class-10/maths/chapter-8/

      • 1
    Leave an answer

    Leave an answer

    Browse