JEE Mains · Physics · STD 11 - 3.1 vectors
If the projection of \(2 \hat{i}+4 \hat{j}-2 \hat{k}\) on \(\hat{i}+2 \hat{j}+\alpha \hat{k}\) is zero. Then, the value of \(\alpha\) will be.
- A \(2\)
- B \(3\)
- C \(5\)
- D \(4\)
Answer & Solution
Correct Answer
(C) \(5\)
Step-by-step Solution
Detailed explanation
\(\overrightarrow{ a } \cdot \overrightarrow{ b }=0\) \(\therefore \overrightarrow{ a } \cdot \overrightarrow{ b }=0\) \(\therefore 2 \times 1+4 \times 2-2 \times \alpha=0\) \(\therefore \alpha=5\)
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