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If p⃗=i^+j^−2k^\vec{p} = \hat{i} + \hat{j} - 2\hat{k} and q⃗=2i^+j^−k^\vec{q} = 2\hat{i} + \hat{j} - \hat{k}, then the area of parallelogram having diagonals (p⃗+q⃗)(\vec{p} + \vec{q}) and (p⃗−q⃗)(\vec{p} - \vec{q}) is

Solution

✅ Correct Option: 3

d1⃗=p⃗+q⃗=3i^+2j^−3k^\vec{d_1} = \vec{p}+\vec{q} = 3\hat{i}+2\hat{j}-3\hat{k}, d2⃗=p⃗−q⃗=−i^−k^\vec{d_2} = \vec{p}-\vec{q} = -\hat{i}-\hat{k}.

d1⃗×d2⃗=−2i^+6j^+2k^\vec{d_1}\times\vec{d_2} = -2\hat{i}+6\hat{j}+2\hat{k}, with magnitude 4+36+4=44=211\sqrt{4+36+4} = \sqrt{44} = 2\sqrt{11}.

Area of parallelogram with diagonals =12∣d1⃗×d2⃗∣=11= \frac{1}{2}|\vec{d_1}\times\vec{d_2}| = \sqrt{11} sq. units.

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