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If a⃗=2i^−2j^+k^\vec{a} = 2\hat{i} - 2\hat{j} + \hat{k}, then which of the following statements are TRUE?

(A) unit vector along a⃗\vec{a} is 13(2i^+2j^−k^)\frac{1}{3}(2\hat{i}+2\hat{j}-\hat{k})

(B) ∣3a⃗∣=9|3\vec{a}| = 9

(C) a⃗\vec{a} is perpendicular to 2i^+3j^+2k^2\hat{i}+3\hat{j}+2\hat{k}

(D) Direction Ratios of a⃗\vec{a} are 2,-2,1

Choose the correct answer from the options given below:

Solution

✅ Correct Option: 2

Here ∣a⃗∣=3|\vec a|=3, so the unit vector is 13(2i^−2j^+k^)\frac13(2\hat i-2\hat j+\hat k) and (A) is false. ∣3a⃗∣=9|3\vec a|=9, so (B) is true. The dot product with 2i^+3j^+2k^2\hat i+3\hat j+2\hat k is 4−6+2=04-6+2=0, so (C) is true. Direction ratios are the components 2,−2,12,-2,1, so (D) is true.

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