Check sibling questions

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

 


Transcript

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)

  1. Class 10
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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