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JEE Main 2021 · MathsMultiple choiceSingle correctMediumApplication

JEE Main 25 February 2021, Shift 2, Maths Q77

Question 77 of 90 in this shift, Maths question 17 of 30, Section A.

If

0 < x, y < \pi

and

\cos x + \cos y - \cos(x+y) = \frac{3}{2}

, then

\sin x + \cos y

is equal to :

(1) $\frac{1}{2}$
(2) $\frac{\sqrt{3}}{2}$
(3) $\frac{1-\sqrt{3}}{2}$
(4) $\frac{1+\sqrt{3}}{2}$ Official answer

Official answer

Option 4

NTA final key.

Chapter: Trigonometric Functions
Topic: Trigonometric Identities
Idea tested: Trigonometric Bounds and Inequalities

Same idea in other shifts

Asked 2× in all

3 Aug 2021, Shift 2 · Q79The maximum value of $(\cos\theta_1)\cdot(\cos\theta_2)\cdot(\cos\theta_3)\cdot\ldots\cdot(\cos\theta_{10})$ under the restrictions…HardSingle correct

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 108 of the 174 JEE Main shifts held from 2017 to 2026.