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Which of the following statements are correct?

A. The unit vector in the direction of the vector a⃗=i^+j^+2k^\vec{a}=\hat{i}+\hat{j}+2\hat{k} is 16i^+16j^+26k^\frac{1}{\sqrt{6}}\hat{i}+\frac{1}{\sqrt{6}}\hat{j}+\frac{2}{\sqrt{6}}\hat{k}.

B. A vector in the direction of the vector 5i^−j^+2k^5\hat{i}-\hat{j}+2\hat{k} which has magnitude 8 units is 40i^−8j^+16k^40\hat{i}-8\hat{j}+16\hat{k}.

C. The vector joining the points P(2, 3, 0) and Q(–1, –2, –4) directed from P to Q is −3i^−5j^−4k^-3\hat{i}-5\hat{j}-4\hat{k}.

D. The position vector of the mid-point of the vector joining the points P(2, 3, 4) and Q(4, 1, –2) is 3i^+2j^−k^3\hat{i}+2\hat{j}-\hat{k}.

Choose the correct answer from the options given below:

Solution

✅ Correct Option: 2

A: ∣a⃗∣=6|\vec a|=\sqrt6, so the stated unit vector is right. C: PQ⃗=Q−P=−3i^−5j^−4k^\vec{PQ}=Q-P=-3\hat i-5\hat j-4\hat k, correct. B fails since 40i^−8j^+16k^40\hat i-8\hat j+16\hat k has magnitude 8308\sqrt{30}, not 8. D fails since the midpoint is (3,2,1)(3,2,1).

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