JEE Main 2022 · MathsMultiple choiceSingle correctMediumMulti-step

JEE Main 28 July 2022, Shift 1, Maths Q6

Question 6 of 90 in this shift, Maths question 6 of 30, Section A.

Let a vector

\vec{a}

has magnitude 9. Let a vector

\vec{b}

be such that for every

(x,y)\in\mathbf{R}\times\mathbf{R}-\{(0,0)\}

, the vector

(x\vec{a}+y\vec{b})

is perpendicular to the vector

(6y\vec{a}-18x\vec{b})

. Then the value of

|\vec{a}\times\vec{b}|

is equal to :

(1) $9\sqrt{3}$
(2) $27\sqrt{3}$ Official answer
(3) $9$
(4) $81$

Official answer

Option 2

NTA final key (2022 Session 2).

Chapter: Vector Algebra
Topic: Dot Product
Idea tested: Orthogonality Condition

Same topic in other shifts

All Dot Product questions

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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.