KVPY2018MathematicsSets and Relations
Let S = x ∈ R : cos x + cos 2 x < 2 , then
Options
- AS = ϕ
- BS is a non-empty finite set
- CS is an infinite proper subset of R - 0
- DS = R - 0
Correct answer
D. S = R - 0
Step-by-step solution
We have, S = x ∈ R : cos x + cos 2 x < 2 Maximum value of cos x and cos 2 x is 1 at x = 0 ∴ cos x + cos 2 x = 2 at x = 0 Hence, S = R - 0