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Match List-I with List-II

List-IList-II
(A) (a⃗−b⃗)×(a⃗+b⃗)(\vec{a}-\vec{b}) \times (\vec{a}+\vec{b}) equals(I) 0⃗\vec{0}
(B) a⃗=(3i^+j^−4k^),b⃗=(6i^+5j^−2k^)\vec{a} = (3\hat{i}+\hat{j}-4\hat{k}), \vec{b} = (6\hat{i}+5\hat{j}-2\hat{k}), then ∣a⃗×b⃗∣\left\vert \vec{a}\times\vec{b} \right\vert equals(II) 55
(C) a⃗×(b⃗+c⃗)+b⃗×(c⃗+a⃗)+c⃗×(a⃗+b⃗)=\vec{a}\times(\vec{b}+\vec{c}) + \vec{b}\times(\vec{c}+\vec{a}) + \vec{c}\times(\vec{a}+\vec{b}) =(III) 2(a⃗×b⃗)2(\vec{a}\times\vec{b})
(D) Projection of vector (i^+3j^+7k^)(\hat{i}+3\hat{j}+7\hat{k}) on vector (2i^−3j^+6k^)(2\hat{i}-3\hat{j}+6\hat{k}) is(IV) 2727

Choose the correct answer from the options given below:

Solution

✅ Correct Option: 4

(A) expands to 2(a⃗×b⃗)2(\vec{a}\times\vec{b}). (B) a⃗×b⃗=18i^−18j^+9k^\vec{a}\times\vec{b} = 18\hat{i}-18\hat{j}+9\hat{k} with magnitude 27. (C) every cross product cancels with its opposite, giving 0⃗\vec{0}. (D) projection =2−9+427=5= \frac{2-9+42}{7} = 5.

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