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MHT CET 202622 AprilEvening Shift
Exam
MHT CET
Year
2026
Date
22 April
Shift
Evening Shift
Subject
Physics
Chapter
Mathematics in Physics

MHT CET 2026 · 22 April · Evening Shift · Physics · Mathematics in Physics

The area of a triangle formed by vectors P = (3 i - 4 j + 2 k ) m...

The area of a triangle formed by vectors P⃗=(3i^−4j^+2k^)\vec{P} = (3\hat{i} - 4\hat{j} + 2\hat{k}) m and Q⃗=(i^+j^−2k^)\vec{Q} = (\hat{i} + \hat{j} - 2\hat{k}) m as adjacent sides is approximately

Options

  1. A12 m212\ \text{m}^2
  2. B6 m26\ \text{m}^2
  3. C14 m214\ \text{m}^2
  4. D7 m27\ \text{m}^2

Correct answer

B. 6 m26\ \text{m}^2

Step-by-step solution

The area of a triangle with adjacent sides P⃗\vec{P} and Q⃗\vec{Q} is given by 12∣P⃗×Q⃗∣\dfrac{1}{2} |\vec{P} \times \vec{Q}|.

Calculating the cross product of the given vectors:

P⃗×Q⃗=∣i^ and j^ and k^3 and −4 and 21 and 1 and −2∣\vec{P} \times \vec{Q} = \begin{vmatrix} \hat{i} \text{ and } \hat{j} \text{ and } \hat{k} \\ 3 \text{ and } -4 \text{ and } 2 \\ 1 \text{ and } 1 \text{ and } -2 \end{vmatrix}

P⃗×Q⃗=i^(8−2)−j^(−6−2)+k^(3+4)=6i^+8j^+7k^\vec{P} \times \vec{Q} = \hat{i}(8 - 2) - \hat{j}(-6 - 2) + \hat{k}(3 + 4) = 6\hat{i} + 8\hat{j} + 7\hat{k}

Finding the magnitude of the cross product:

∣P⃗×Q⃗∣=62+82+72=36+64+49=149|\vec{P} \times \vec{Q}| = \sqrt{6^2 + 8^2 + 7^2} = \sqrt{36 + 64 + 49} = \sqrt{149}

The area of the triangle is:

Area=12149≈12.22=6.1\text{Area} = \dfrac{1}{2} \sqrt{149} \approx \dfrac{12.2}{2} = 6.1

Approximating to the nearest integer, the numerical value of the area is 66.

Answer: 6 m26\ \text{m}^2
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