Chapter 8 Class 10 Introduction to Trignometry

Class 10
Important Questions for Exam - Class 10

### Transcript

Ex 8.1, 9 In triangle ABC, right-angled at B, if tan A = 1/β3, find the value of sin A cos C + cos A sin C Given tan A = 1/β3 (πΊπππ ππππππππ ππ π¨)/(πΊπππ ππππππππ ππ π¨) = π/βπ π΅πΆ/π΄π΅ = 1/β3 Let BC = x & AB = βπ x We have to find sin A cos C + cos A sin C Putting sin A = 1/2 , cos A = β3/2 , sin C = β3/2 & cos C = 1/2 = (π/π)Γ(π/π)+(βπ/π)Γ(βπ/π) = 1/4 + (β3 Γ β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/β3, find the value of (ii) cos A cos C β sin A sin C cos A cos C β sin A sin C Putting sin A = 1/2 , cos A = β3/2 , sin C = β3/2 & cos C = 1/2 = (βπ/π)Γπ/πβ(π/π)Γ(βπ/π) = (β3/4)β(β3/4) = 0 Hence, cos A cos C β sin A sin C = 0