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:6
If angle A and angle B are acute angles such that cos A = cos B, then show that angle A = angle B.
Share
Given that: cos A= cos B
cos A = cos B
⇒ AP/AQ = BC/BD
⇒ AP/BC = AQ/BD
Let AP/BC = AQ/BC = k …(i)
Therefore, AP = k(BC) and AQ = k(BD)
Now, In △APQ and △BCD
PQ/CD = √((AQ²-AP²))/(√(BD²-BC²))
= (√((k.BD)²-(k.BC)²))/(√(BD²-BC²))
= (k√(BD²-BC²))/(√(BD²-BC²)) = k …(ii)
From the equation (i) and (ii), we get
AP/BC = AQ/BD = PQ/CD
So, △APQ ∼ △BCD [SSS similarity criteria]
Hence, ∠A = ∠B
Video explanation of this question👌🤗
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/