Q. 7

# Write the values of x in [0, π] for which and cos 2x are in A.P.

a, a+r, a+2r

so A1+A3=2A2

here sin2x + cos2x = 1

2sin x cos x + 1-2sin2x =1

sin x cos x - sin2x=0

sin x (cos x-sin x)=0

if sin x =0

then x =0, π

if sin x=cos x

then x = π/4

So, all possible values are

Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos
Interactive Quiz on trigonometric identities & equations52 mins
Conditional IdentitiesFREE Class
Trigonometric Functions - 0152 mins
Trigonometric Series45 mins
Trigonometric Functions - 0568 mins
Trigonometric Functions - 0658 mins
Trigonometric Functions - 0366 mins
Interactive Quiz on trigonometric ratios & identities73 mins
Trigonometric Functions - 0268 mins
Trigonometric Functions - 0466 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
view all courses