If cos 9α = sin α and 9α < 90° , then the value of tan 5α is

(A) 1/√3   (B) √3   (C) 1  (D) 0

Slide15.JPG

Advertisement

Slide16.JPG

Advertisement

  1. Chapter 8 Class 10 Introduction to Trignometry (Term 1)
  2. Serial order wise

Transcript

Question 10 If cos 9α = sin α and 9α < 90° , then the value of tan 5α is (A) 1/√3 (B) √3 (C) 1 (D) 0 Given cos 9α = sin α cos 9α = cos (90° − α) Comparing angles 9α = 90° − α 9α + α = 90° 10α = 90° α = (90° )/(10° ) α = 9° Now, tan 5α = tan (5 × 9°) = tan 45° = 1 So, the correct answer is (C)

About the Author

Davneet Singh's photo - Teacher, Engineer, Marketer
Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 10 years. He provides courses for Maths and Science at Teachoo.