1. Chapter 8 Class 10 Introduction to Trignometry
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Question 7 - NCERT Exemplar - MCQ - Chapter 8 Class 10 Introduction to Trignometry

Last updated at Dec. 16, 2024 by Teachoo

Given that sin θ = a/b, then cos θ is equal to

(A) b/√(b^2  - a^2 )   

(B) b/a  

(C) √(b^2  - a^2 )/b   

(D) a/√(b^2  - a^2 )

Transcript

Question 7 Given that sin θ = 𝑎/𝑏, then cos θ is equal to (A) 𝑏/√(𝑏^2 − 𝑎^2 ) (B) 𝑏/𝑎 (C) √(𝑏^2 − 𝑎^2 )/𝑏 (D) 𝑎/√(𝑏^2 − 𝑎^2 ) Now, cos2 θ = 1 − sin2 θ Putting sin θ = 𝑎/𝑏 cos2 θ = 1−(𝑎/𝑏)^2 cos2 θ = 1−𝑎^2/𝑏^2 cos2 θ = (𝒃^𝟐 − 𝒂^𝟐)/𝒃^𝟐 Taking square root cos θ = ± √((𝑏^2 − 𝑎^2)/𝑏^2 ) cos θ = ± √(𝑏^2 − 𝑎^2 )/𝑏 Since only positive values are given in options cos θ = √(𝒃^𝟐 − 𝒂^𝟐 )/𝒃 So, the correct answer is (C)
  1. Chapter 8 Class 10 Introduction to Trignometry
  2. Serial order wise

    3. NCERT Exemplar - MCQ

    sin 90 - θ, cos 90 - θ formula →
sin 90 - θ, cos 90 - θ formula →
Chapter 8 Class 10 Introduction to Trignometry
Serial order wise

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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