Class 12 Math Case Study Vectors with Answers – NCERT Based

Chapter: Class 12 Math Case Study Vectors with Answers

The chapter on Class 12 Math Case Study Vectors with Answers introduces students to essential vector algebra skills through solved case study problems. Moreover, each solution is explained clearly to help students understand key concepts quickly. These questions follow the Class 12 exam pattern, and therefore they help students gain confidence while preparing for tests.

Important Vector Concepts Included

This section highlights dot product, cross product, vector projections, and direction ratios. Additionally, students learn how to apply these concepts in real situations. These examples build strong analytical abilities.

Benefits for Class 12 Students

These solved case studies improve revision and problem accuracy. Consequently, students prepare effectively for board exams. This structured approach also strengthens conceptual clarity.

Class 12 Math Case Study Vectors with Answers

In a space research lab, engineers are developing a satellite launch simulation model. To program the movement of the satellite in 3D space, they need to calculate the **position and direction of motion** at various stages. Every motion is **resolved into components** along the three coordinate axes. They study how vectors can be expressed in terms of **direction cosines**, direction ratios, and unit vectors. By using the **position vector**, they determine the precise location of the satellite at any instant. Direction cosines help in analyzing the orientation of movement in space. All the engineers must be proficient in converting vectors from geometric to component form in both 2D and 3D, which is essential for accurate navigation.

Theory and Formulae Related to Vector Components:

  • Resolution in 3D: $\vec{a} = a_1\hat{i} + a_2\hat{j} + a_3\hat{k}$
  • Magnitude: $|\vec{a}| = \sqrt{a_1^2 + a_2^2 + a_3^2}$
  • Direction cosines: $\cos\alpha = \frac{a_1}{|\vec{a}|}, \cos\beta = \frac{a_2}{|\vec{a}|}, \cos\gamma = \frac{a_3}{|\vec{a}|}$
  • Property: $\cos^2\alpha + \cos^2\beta + \cos^2\gamma = 1$
  • Position vector of a point $P(x, y, z)$ is $\vec{OP} = x\hat{i} + y\hat{j} + z\hat{k}$

1. What is the position vector of the point $P(3, -2, 5)$?

Solution: The position vector of a point $P(x, y, z)$ is $\vec{OP} = x\hat{i} + y\hat{j} + z\hat{k}$. Thus, for $P(3, -2, 5)$, the vector is $3\hat{i} – 2\hat{j} + 5\hat{k}$.
Correct answer is option **(a)**.

2. If $\vec{a} = 4\hat{i} + 3\hat{j} + 12\hat{k}$, find its magnitude.

Solution: The magnitude is calculated as $|\vec{a}| = \sqrt{4^2 + 3^2 + 12^2} = \sqrt{16 + 9 + 144} = \sqrt{169}$. Since $\sqrt{169} = 13$, option (a) is the final answer.
Correct answer is option **(a)**.

3. If a vector makes angles $\alpha, \beta, \gamma$ with the coordinate axes and the direction cosines are $\cos\alpha = \frac{3}{13}, \cos\beta = \frac{4}{13}, \cos\gamma = \frac{12}{13}$, then verify the identity.

Solution: The fundamental identity for direction cosines ($l, m, n$) is $l^2 + m^2 + n^2 = 1$. Verification: $\left( \frac{3}{13} \right)^2 + \left( \frac{4}{13} \right)^2 + \left( \frac{12}{13} \right)^2 = \frac{9 + 16 + 144}{169} = \frac{169}{169} = 1$.
Correct answer is option **(b)**.

4. Find the direction cosines of vector $\vec{a} = 6\hat{i} – 3\hat{j} + 2\hat{k}$

Solution: First, find the magnitude: $|\vec{a}| = \sqrt{6^2 + (-3)^2 + 2^2} = \sqrt{36 + 9 + 4} = \sqrt{49} = 7$. The direction cosines are the components divided by the magnitude: $\frac{6}{7}, \frac{-3}{7}, \frac{2}{7}$.
Correct answer is option **(a)**.

5. Which of the following is correct about the direction cosines of any vector?

Solution: The sum of the squares of the direction cosines of any vector is always 1.
Correct answer is option **(c)**.

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