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Let a⃗\vec{a} and b⃗\vec{b} be any two vectors such that a⃗=2i^+j^+3k^\vec{a} = 2\hat{i} + \hat{j} + 3\hat{k} and b⃗=3i^+5j^−2k^\vec{b} = 3\hat{i} + 5\hat{j} - 2\hat{k} then

Match the LIST-I with LIST-II

LIST-ILIST-II
A.∣a⃗∣\vert \vec{a} \vertI.55
B.∣b⃗∣\vert \vec{b} \vertII.507\sqrt{507}
C.∣a⃗.b⃗∣\vert \vec{a}.\vec{b} \vertIII.38\sqrt{38}
D.∣a⃗×b⃗∣\vert \vec{a} \times \vec{b} \vertIV.14\sqrt{14}

Choose the correct answer from the options given below:

Solution

✅ Correct Option: 4

∣a⃗∣=4+1+9=14|\vec a| = \sqrt{4+1+9} = \sqrt{14} (IV) and ∣b⃗∣=9+25+4=38|\vec b| = \sqrt{9+25+4} = \sqrt{38} (III).

a⃗⋅b⃗=6+5−6=5\vec a\cdot\vec b = 6+5-6 = 5 (I).

Using ∣a⃗×b⃗∣2=∣a⃗∣2∣b⃗∣2−(a⃗⋅b⃗)2=532−25|\vec a\times\vec b|^2 = |\vec a|^2|\vec b|^2 - (\vec a\cdot\vec b)^2 = 532-25, we get 507\sqrt{507} (II).

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