Let a = αi + j − k and b = 2i + j... |JEE Main 2022 | Vector

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JEE MAIN_2022

26-07-2022_S1

Question

Let $\vec{a}=\alpha \hat{i}+\hat{j}-\hat{k}$ and $\vec{b}=2 \hat{i}+\hat{j}-\alpha \hat{k}, \alpha>0$. If the projection of $\vec{a} \times \vec{b}$ on the vector $-\hat{i}+2 \hat{j}-2 \hat{k}$ is 30 , then $\alpha$ is equal

Select the correct option:

A

$\frac{15}{2}$

B

8

C

$\frac{13}{2}$

D

7

✓ Correct! Well done.

✗ Incorrect. Try again or view the solution.

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