Class CBSE Class 12 Mathematics Three Dimensional Geometry Q #1449
KNOWLEDGE BASED
REMEMBER
2 Marks 2025 AISSCE(Board Exam) VSA
Determine if the lines $\vec{r}=(\hat{i}+\hat{j}-\hat{k})+\lambda(3\hat{i}-\hat{j})$ and $\vec{r}=(4\hat{i}-\hat{k})+\mu(2\hat{i}+3\hat{k})$ intersect with each other.

AI Tutor Explanation

Powered by Gemini

Detailed Solution

Step 1: Write the equations of the lines in parametric form

The given lines are: $\vec{r}=(\hat{i}+\hat{j}-\hat{k})+\lambda(3\hat{i}-\hat{j})$ and $\vec{r}=(4\hat{i}-\hat{k})+\mu(2\hat{i}+3\hat{k})$. We can write these in parametric form as: Line 1: $x = 1 + 3\lambda$ $y = 1 - \lambda$ $z = -1$ Line 2: $x = 4 + 2\mu$ $y = 0$ $z = -1 + 3\mu$

Step 2: Check for intersection

For the lines to intersect, there must exist values of $\lambda$ and $\mu$ such that the coordinates $(x, y, z)$ are the same for both lines. Therefore, we set the corresponding coordinates equal to each other: $1 + 3\lambda = 4 + 2\mu$ (1) $1 - \lambda = 0$ (2) $-1 = -1 + 3\mu$ (3)

Step 3: Solve the system of equations

From equation (2), we have $\lambda = 1$. From equation (3), we have $3\mu = 0$, so $\mu = 0$. Substitute $\lambda = 1$ and $\mu = 0$ into equation (1): $1 + 3(1) = 4 + 2(0)$ $1 + 3 = 4$ $4 = 4$ Since the equation holds true, the lines intersect.

Step 4: Find the point of intersection

Using $\lambda = 1$ in the equation for Line 1: $x = 1 + 3(1) = 4$ $y = 1 - (1) = 0$ $z = -1$ So, the point of intersection is $(4, 0, -1)$. Using $\mu = 0$ in the equation for Line 2: $x = 4 + 2(0) = 4$ $y = 0$ $z = -1 + 3(0) = -1$ So, the point of intersection is $(4, 0, -1)$.

Final Answer: Yes, the lines intersect.<\/span>

AI generated content. Review strictly for academic accuracy.

Pedagogical Audit
Bloom's Analysis: This is an REMEMBER question because it requires recalling the conditions for intersection of lines in 3D space and applying the standard procedure to check for intersection.
Knowledge Dimension: PROCEDURAL
Justification: The question requires applying a specific algorithm or method to determine if two lines intersect. This involves setting up equations and solving for parameters, which is a procedural skill.
Syllabus Audit: In the context of CBSE Class 12, this is classified as KNOWLEDGE. The question directly tests the student's understanding of the conditions for intersection of lines in 3D geometry, a standard topic in the syllabus.