The complete solution of inequality cos 2x ≤ cos x is

Maths Trigonometrical Ratios, Functions and Identities Trigonometric Inquations and Height & Distance Single Correct MCQ

Published by: CGP EDU Academic Team

Published on: August 12, 2026

x ∈

Text Solution

Verified by Experts

The correct answer is:

cos 2x ≤ cos x ⇒ 2 cos 2 x – cos x – 1 ≤ 0 ⇒ 2 cos 2 x – 2 cos x + cos x – 1 ≤ 0

⇒ 2 cos x (cos x – 1) + 1(cos x – 1) ≤ 0 ⇒ (cos x – 1) (2 cos x + 1) ≤ 0

⇒ cos x ∈ ∴ x ∈ General soltution is x ∈ .

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