JEE Main 2024 · MathsMultiple choiceSingle correctMediumMulti-step

JEE Main 9 April 2024, Shift 1, Maths Q20

Question 20 of 90 in this shift, Maths question 20 of 30, Section A.

Let

\left|\cos\theta\cos(60^\circ-\theta)\cos(60^\circ+\theta)\right|\le\frac{1}{8}

\theta\in[0,2\pi]

. Then, the sum of all

\theta\in[0,2\pi]

, where

\cos3\theta

attains its maximum value, is :

(1) $6\pi$ Official answer
(2) $18\pi$
(3) $9\pi$
(4) $15\pi$

Official answer

Option 1

NTA final key.

Chapter: Trigonometric Functions
Topic: Trigonometric Identities
Idea tested: Cosine Product Identity with 60 Degrees

Same topic in other shifts

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Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 42 of the 174 JEE Main shifts held from 2017 to 2026.