Class CBSE Class 12 Mathematics Vector Algebra Q #816
KNOWLEDGE BASED
REMEMBER
1 Marks 2023 MCQ SINGLE
Two vectors →a = a₁î + a₂î + a₃ê and →b = b₁î + b₂î + b₃ê are collinear if
(A) a₁b₁ + a₂b₂ + a₃b₃ = 0
(B) a₁/b₁ = a₂/b₂ = a₃/b₃
(C) a₁=b₁, a₂=b₂, a₃=b₃
(D) a₁+a₂+a₃ = b₁+b₂+b₃

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Step-by-Step Solution

Two vectors →a and →b are collinear if they are parallel, meaning one is a scalar multiple of the other. This can be expressed as →a = λ→b, where λ is a scalar.

Given →a = a₁î + a₂ĵ + a₃k̂ and →b = b₁î + b₂ĵ + b₃k̂, the collinearity condition implies:

a₁î + a₂ĵ + a₃k̂ = λ(b₁î + b₂ĵ + b₃k̂)

This leads to the following relationships:

a₁ = λb₁, a₂ = λb₂, a₃ = λb₃

From these equations, we can derive:

λ = a₁/b₁ = a₂/b₂ = a₃/b₃

This condition is represented by option (B).

Correct Answer: a₁/b₁ = a₂/b₂ = a₃/b₃

AI Suggestion: Option B

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Pedagogical Audit
Bloom's Analysis: This is an REMEMBER question because it directly tests the student's ability to recall the condition for collinearity of two vectors.
Knowledge Dimension: CONCEPTUAL
Justification: The question requires understanding the concept of collinearity of vectors and its mathematical representation.
Syllabus Audit: In the context of CBSE Class 12, this is classified as KNOWLEDGE. The question directly assesses the knowledge of a specific definition or condition related to vectors, which is typically covered in textbooks.