Ex 8.1, 9 - Chapter 8 Class 10 Introduction to Trignometry

Last updated at August 2, 2026 by

Ex 8.1, 9 - In ABC, if tan A = 1/ root 3, find sin A cos C - Ex 8.1

part 2 - Ex 8.1, 9 - Ex 8.1 - Serial order wise - Chapter 8 Class 10 Introduction to Trignometry
part 3 - Ex 8.1, 9 - Ex 8.1 - Serial order wise - Chapter 8 Class 10 Introduction to Trignometry part 4 - Ex 8.1, 9 - Ex 8.1 - Serial order wise - Chapter 8 Class 10 Introduction to Trignometry

part 5 - Ex 8.1, 9 - Ex 8.1 - Serial order wise - Chapter 8 Class 10 Introduction to Trignometry

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Ex 8.1, 9 In triangle ABC, right-angled at B, if tan A = 1/√3, find the value of sin A cos C + cos A sin C Given tan A = 1/√3 (π‘Ίπ’Šπ’…π’† π’π’‘π’‘π’π’”π’Šπ’•π’† 𝒕𝒐 𝑨)/(π‘Ίπ’Šπ’…π’† 𝒂𝒅𝒋𝒂𝒄𝒆𝒏𝒕 𝒕𝒐 𝑨) = 𝟏/βˆšπŸ‘ 𝐡𝐢/𝐴𝐡 = 1/√3 Let BC = x & AB = βˆšπŸ‘ x We have to find sin A cos C + cos A sin C Putting sin A = 1/2 , cos A = √3/2 , sin C = √3/2 & cos C = 1/2 = (𝟏/𝟐)Γ—(𝟏/𝟐)+(βˆšπŸ‘/𝟐)Γ—(βˆšπŸ‘/𝟐) = 1/4 + (√3 Γ— √3)/4 = 1/4 + 3/4 = (1 + 3)/4 = 4/4 = 1 So, sin A cos C + cos A sin C = 1 Ex 8.1, 9 In triangle ABC, right-angled at B, if tan A = 1/√3, find the value of (ii) cos A cos C – sin A sin C cos A cos C – sin A sin C Putting sin A = 1/2 , cos A = √3/2 , sin C = √3/2 & cos C = 1/2 = (βˆšπŸ‘/𝟐)Γ—πŸ/πŸβˆ’(𝟏/𝟐)Γ—(βˆšπŸ‘/𝟐) = (√3/4)βˆ’(√3/4) = 0 Hence, cos A cos C – sin A sin C = 0

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