JEE Mains · Maths · STD 12 - 10. vector algebra
If \(\overrightarrow {{{\left| c \right|}^2}} = 60\) and \(\overrightarrow c \times \left( {\hat i + 2\hat j + 5\hat k} \right) = \overrightarrow 0 \), then a value of \(\overrightarrow c .\left( { - 7\hat i + 2\hat j + 3\hat k} \right)\) is
- A \(4\sqrt 2 \)
- B \(12\)
- C \(24\)
- D \(12\sqrt 2 \)
Answer & Solution
Correct Answer
(D) \(12\sqrt 2 \)
Step-by-step Solution
Detailed explanation
Let, \(\vec{c}=a \hat{i}+b \hat{j}+c \hat{k}\) Given, \(\vec{c} \times(\hat{i}+2 \hat{j}+5 \hat{k})=\overline{0}\) \( \Rightarrow \begin{array}{*{20}{c}} {\hat i}&{\hat i}&{\hat k}\\ a&b&c\\ 1&2&5 \end{array} = \overline 0 \)…
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