1
COMEDK 2023 Evening Shift
MCQ (Single Correct Answer)
+1
-0

The scalar components of a unit vector which is perpendicular to each of the vectors $$\hat{\imath}+2 \hat{\jmath}-\hat{k}$$ and $$3 \hat{\imath}-\hat{\jmath}+2 \hat{k}$$ are

A
$$ -\frac{3}{\sqrt{83}}, \quad-\frac{5}{\sqrt{83}}, \quad \frac{7}{\sqrt{83}} $$
B
$$ -3, \quad-5, \quad 7 $$
C
$$ \frac{3}{\sqrt{83}}, \quad-\frac{5}{\sqrt{83}}, \quad-\frac{7}{\sqrt{83}} $$
D
$$ 3, \quad-5, \quad-7 $$
2
COMEDK 2023 Evening Shift
MCQ (Single Correct Answer)
+1
-0

$$ \text { If } \vec{a} \text { and } \vec{b} \text { are unit vectors, then the angle between } \vec{a} \text { and } \vec{b} \text { for which } a-\sqrt{2} \vec{b} \text { is a unit vector is } $$

A
$$ \frac{\pi}{3} $$
B
$$ \frac{\pi}{2} $$
C
$$ \frac{\pi}{6} $$
D
$$ \frac{\pi}{4} $$
3
COMEDK 2022
MCQ (Single Correct Answer)
+1
-0

If $$\theta$$ be the angle between the vectors $$a = 2\widehat i + 2\widehat j - \widehat k$$ and $$b = 6\widehat i - 3\widehat j + 2\widehat k$$, then

A
$$\cos \theta = {4 \over {21}}$$
B
$$\cos \theta = {3 \over {19}}$$
C
$$\cos \theta = {2 \over {19}}$$
D
$$\cos \theta = {5 \over {21}}$$
4
COMEDK 2022
MCQ (Single Correct Answer)
+1
-0

If x, y and z are non-zero real numbers and $$a = x\widehat i + 2\widehat j,b = y\widehat j + 3\widehat k$$ and $$c = x\widehat i + y\widehat j + z\widehat k$$ are such that $$a \times b = z\widehat i - 3\widehat j + \widehat k$$, then [a b c] is equal to

A
3
B
10
C
9
D
6
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