Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Vectors

Question:

Match List-I with List-II

List-I List-II
(A) Area of triangle Δ with adjacent sides $\vec{a}$ and $\vec{b}$ (I) $\vec{a}×\vec{b}$
(B) Area of parallelogram with adjacent side $\vec{a}×\vec{b}$ (II) $\frac{1}{2}|\vec{a}×\vec{b}|$
(C) $(\vec{a}-\vec{b})×(\vec{a}+\vec{b})$ (III) $|\vec{a}×\vec{b}|$
(D) $|\vec{a}||\vec{b}|sin \theta \hat{n}$, where symbols have their usual meaning (IV) $2(\vec{a}×\vec{b})$

Choose the correct answer from the options given below :

Options:

(A)-(III),(B)-(IV), (C)-(I), (D)-(II)

(A)-(IV),(B)-(I), (C)-(III), (D)-(II)

(A)-(II),(B)-(III), (C)-(IV), (D)-(I)

(A)-(II),(B)-(IV), (C)-(III), (D)-(I)

Correct Answer:

(A)-(II),(B)-(III), (C)-(IV), (D)-(I)

Explanation:

The correct answer is option (3) → (A)-(II),(B)-(III), (C)-(IV), (D)-(I)

(A) → $\frac{1}{2}|\vec{a}×\vec{b}|$ (II)

(B) → $|\vec{a}×\vec{b}|$ (III)

(C) $(\vec{a}-\vec{b})×(\vec{a}+\vec{b})$

$=\vec a ×\vec a+\vec a×\vec b-\vec b×\vec a-\vec b×\vec b$

$=\vec a×\vec b+\vec a×\vec b=2(\vec a×\vec b)$ (IV)

(D) $|\vec{a}||\vec{b}|\sin \theta \hat{n}=\vec a×\vec b$ (I)