Class CBSE Class 12 Mathematics Three Dimensional Geometry Q #672
KNOWLEDGE BASED
APPLY
1 Marks 2025 AISSCE(Board Exam) MCQ SINGLE
The line \(x=1+5\mu\), \(y=-5+\mu\), \(z=-6-3\mu\) passes through which of the following point ?
(A) \((1, -5, 6)\)
(B) \((1, 5, 6)\)
(C) \((1, -5, -6)\)
(D) \((-1, -5, 6)\)
Correct Answer: C
Explanation
\((1, -5, -6)\)

AI Tutor Explanation

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Step-by-Step Solution

Let's check each point to see if it lies on the line \(x=1+5\mu\), \(y=-5+\mu\), \(z=-6-3\mu\).

(A) \((1, -5, 6)\)

If this point lies on the line, there must be a value of \(\mu\) that satisfies all three equations:

\(1 = 1 + 5\mu \Rightarrow 5\mu = 0 \Rightarrow \mu = 0\)

\(-5 = -5 + \mu \Rightarrow \mu = 0\)

\(6 = -6 - 3\mu \Rightarrow 12 = -3\mu \Rightarrow \mu = -4\)

Since the values of \(\mu\) are not consistent, point (A) does not lie on the line.

(B) \((1, 5, 6)\)

\(1 = 1 + 5\mu \Rightarrow \mu = 0\)

\(5 = -5 + \mu \Rightarrow \mu = 10\)

\(6 = -6 - 3\mu \Rightarrow 12 = -3\mu \Rightarrow \mu = -4\)

Since the values of \(\mu\) are not consistent, point (B) does not lie on the line.

(C) \((1, -5, -6)\)

\(1 = 1 + 5\mu \Rightarrow \mu = 0\)

\(-5 = -5 + \mu \Rightarrow \mu = 0\)

\(-6 = -6 - 3\mu \Rightarrow -3\mu = 0 \Rightarrow \mu = 0\)

Since \(\mu = 0\) satisfies all three equations, point (C) lies on the line.

(D) \((-1, -5, 6)\)

\(-1 = 1 + 5\mu \Rightarrow 5\mu = -2 \Rightarrow \mu = -\frac{2}{5}\)

\(-5 = -5 + \mu \Rightarrow \mu = 0\)

\(6 = -6 - 3\mu \Rightarrow 12 = -3\mu \Rightarrow \mu = -4\)

Since the values of \(\mu\) are not consistent, point (D) does not lie on the line.

Correct Answer: (C) \((1, -5, -6)\)

AI Suggestion: Option C

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Pedagogical Audit
Bloom's Analysis: This is an APPLY question because the student needs to apply the given parametric equation of a line to check which point satisfies the equation.
Knowledge Dimension: PROCEDURAL
Justification: The question requires the student to follow a procedure of substituting the given points into the equation of the line to find the correct answer.
Syllabus Audit: In the context of CBSE Class 12, this is classified as KNOWLEDGE. The question directly tests the student's understanding of the equation of a line in 3D space, a concept covered in the textbook.