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JEE Main 2021 · MathsMultiple choiceSingle correctMediumCalculation

JEE Main 26 August 2021, Shift 2, Maths Q80

Question 80 of 90 in this shift, Maths question 20 of 30, Section A.

The value of

2\sin\left(\frac{\pi}{8}\right)\sin\left(\frac{2\pi}{8}\right)\sin\left(\frac{3\pi}{8}\right)\sin\left(\frac{5\pi}{8}\right)\sin\left(\frac{6\pi}{8}\right)\sin\left(\frac{7\pi}{8}\right)

is :

(1) $\frac{1}{8}$ Official answer
(2) $\frac{1}{8\sqrt{2}}$
(3) $\frac{1}{4}$
(4) $\frac{1}{4\sqrt{2}}$

Official answer

Option 1

NTA final key.

Chapter: Trigonometric Functions
Topic: Trigonometric Identities
Idea tested: Product to Sum Formulas

Same idea in other shifts

Asked 2× in all

9 Jan 2020, Shift 1 · Q69The value of…MediumSingle 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.