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The area of the parallelogram whose adjacent sides are determined by the vectors a⃗=i^−j^+3k^\vec{a} = \hat{i} - \hat{j} + 3\hat{k} and b⃗=2i^−7j^+k^\vec{b} = 2\hat{i} - 7\hat{j} + \hat{k} is :

Solution

✅ Correct Option: 2

a⃗×b⃗=∣i^j^k^1−132−71∣=i^(−1+21)−j^(1−6)+k^(−7+2)=20i^+5j^−5k^\vec{a}\times\vec{b} = \begin{vmatrix}\hat{i}&\hat{j}&\hat{k}\\1&-1&3\\2&-7&1\end{vmatrix} = \hat{i}(-1+21) - \hat{j}(1-6) + \hat{k}(-7+2) = 20\hat{i} + 5\hat{j} - 5\hat{k}. ∣a⃗×b⃗∣=400+25+25=450=152|\vec{a}\times\vec{b}| = \sqrt{400+25+25} = \sqrt{450} = 15\sqrt{2}.

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