LIVE Course for free

Rated by 1 million+ students
Get app now
0 votes
11 views
in Aptitude by (30.0k points)
closed by

Cosθ – sinθ = 4/7 then find the value of (1 – 2 sinθ) × (cos 2θ)


1. 1/7
2. 25/49
3. 16/49
4. 0 
5. 25/36

1 Answer

0 votes
by (30.0k points)
selected by
 
Best answer
Correct Answer - Option 3 : 16/49

Given :

Cosθ – sinθ = 4/7

Formula used :

Cos 2θ = 1 – 2 sinθ = cosθ – sinθ

Sinθ + cosθ = 1

Calculations :

Cosθ – sinθ = 4/7

(cosθ + sinθ )(Cosθ – sinθ) = 4/7

Cosθ – sinθ = 4/7

Now

(1 – 2 sinθ) × (cos 2θ) = (cosθ – sinθ) (cosθ – sinθ)

⇒ (4/7) × (4/7)

⇒ 16/49

∴ 16/49 will be the correct answer 

Welcome to Sarthaks eConnect: A unique platform where students can interact with teachers/experts/students to get solutions to their queries. Students (upto class 10+2) preparing for All Government Exams, CBSE Board Exam, ICSE Board Exam, State Board Exam, JEE (Mains+Advance) and NEET can ask questions from any subject and get quick answers by subject teachers/ experts/mentors/students.

Categories

...