Class CBSE Class 12 Mathematics Three Dimensional Geometry Q #663
KNOWLEDGE BASED
APPLY
1 Marks 2024 AISSCE(Board Exam) MCQ SINGLE
The vector equation of a line passing through the point (1, -1, 0) and parallel to Y-axis is :
(A) \(\vec{r}=\hat{i}-\hat{j}+\lambda(\hat{i}-\hat{j})\)
(B) \(\vec{r}=\hat{i}-\hat{j}+\lambda\hat{j}\)
(C) \(\vec{r}=\hat{i}-\hat{j}+\lambda\hat{k}\)
(D) \(\vec{r}=\lambda\hat{j}\)
Correct Answer: B

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Step-by-Step Solution

The vector equation of a line passing through a point with position vector \(\vec{a}\) and parallel to a vector \(\vec{b}\) is given by: \(\vec{r} = \vec{a} + \lambda\vec{b}\), where \(\lambda\) is a scalar.

Here, the line passes through the point (1, -1, 0), so the position vector \(\vec{a}\) is given by: \(\vec{a} = \hat{i} - \hat{j} + 0\hat{k} = \hat{i} - \hat{j}\)

The line is parallel to the Y-axis, so the direction vector \(\vec{b}\) is given by: \(\vec{b} = \hat{j}\)

Therefore, the vector equation of the line is: \(\vec{r} = (\hat{i} - \hat{j}) + \lambda\hat{j}\)

Correct Answer: \(\vec{r}=\hat{i}-\hat{j}+\lambda\hat{j}\)

AI Suggestion: Option B

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Pedagogical Audit
Bloom's Analysis: This is an APPLY question because the student needs to apply the formula for the vector equation of a line given a point and a parallel vector.
Knowledge Dimension: PROCEDURAL
Justification: The question requires the student to execute a procedure, namely, constructing the vector equation of a line using the given point and direction vector.
Syllabus Audit: In the context of CBSE Class 12, this is classified as KNOWLEDGE. The question directly tests the student's understanding of vector equations of lines, a concept covered in the textbook.