In ∆ABC right angled at B, if tan A = √3, then cos A cos C - sin A sin C =

(a) 1   (b) 0   (c) 1   (d) √3  /2

 

This question is inspired from Ex 8.1, 9 - Chapter 8 Class 10 - Introduction to Trignometry

 

Ques 13 (MCQ) - In ∆ABC, if tan A= √3, then cos A cos C - sin A sin C - CBSE Class 10 Sample Paper for 2022 Boards - Maths Standard [MCQ]

part 2 - Question 13 - CBSE Class 10 Sample Paper for 2022 Boards - Maths Standard [MCQ] - Solutions of Sample Papers for Class 10 Boards - Class 10

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Question 13 In ∆ABC right angled at B, if tan A = √3, then cos A cos C - sin A sin C = (a) 1 (b) 0 (c) 1 (d) √3 /2 Given, tan A = √3 ∴ ∠ A = 60° Now, In Δ ABC By Angle sum property ∠ A + ∠ B + ∠ C = 180° 60° + 90° + ∠ C = 180° 150° + ∠ C = 180° ∠ C = 180° − 150° ∠ C = 30° Now, cos A cos C − sin A sin C = cos 60° cos 30° − sin 60° sin 30° = 1/2 × √3/2 − √3/2 × 1/2 = 0 So, the correct answer is (b)

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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