1. Chapter 8 Class 10 Introduction to Trignometry
  2. Serial order wise
  3. Sin 90 - θ, cos 90 - θ formula
Check sibling questions

Question 6 - sin 90 - θ, cos 90 - θ formula - Chapter 8 Class 10 Introduction to Trignometry

Last updated at Dec. 13, 2024 by Teachoo

Transcript

Question 6 If A, B and C are interior angles of a triangle ABC, then show that sin ((B + C)/2)= cos 𝐴/2 In Δ ABC Sum of angles of a triangle = 180 ° A + B + C = 180° B + C = 180° – A Multiplying both sides by 1/2 (𝐵 + 𝐶)/2 " = " (180° − 𝐴)/2 (𝐵 + 𝐶)/2 " = " (180°)/2 – 𝐴/2 (𝐵 + 𝐶)/2 " = " 90° – 𝐴/2 Taking L.H.S sin ((𝐵 + 𝐶)/2) = sin ("90° − " ( 𝐴)/2) = 𝑐𝑜𝑠 𝐴/2 = R.H.S Hence proved
  1. Chapter 8 Class 10 Introduction to Trignometry
  2. Serial order wise

    3. Sin 90 - θ, cos 90 - θ formula

    Finding sin cos tan →
Finding sin cos tan →
Chapter 8 Class 10 Introduction to Trignometry
Serial order wise

About the Author

Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science and Computer Science at Teachoo