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Saturday, 31 October

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JEE Main 2021 · MathsMultiple choiceSingle correctHardCalculation

JEE Main 4 August 2021, Shift 1, Maths Q75

Question 75 of 90 in this shift, Maths question 15 of 30, Section A.

If the ellipse

\frac{x^2}{16}+\frac{y^2}{b^2}=1

and the circle

x^2+y^2=4b

intersect at an angle

\frac{\pi}{3}

, then a value of 'b' is

(1) $10+2\sqrt{21}$ Official answer
(2) $20+2\sqrt{21}$
(3) $10-3\sqrt{21}$
(4) $20-3\sqrt{21}$

Official answer

Option 1

NTA final key.

Chapter: Conic Sections
Topic: Tangents and Normals
Idea tested: Angle Between Curves

Same idea in other shifts

Asked 2× in all

31 Aug 2021, Shift 2 · Q66An angle of intersection of the curves, $\frac{x^2}{\mathrm{a}^2}+\frac{y^2}{\mathrm{b}^2} = 1$ and $x^2+y^2 = \mathrm{ab}$ ,…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.