1
NDA 2015 Paper 2
MCQ (Single Correct Answer)
+2.5
-0.83
If | a | = 2 and | b | = 3, then, | a $$\times$$ b |2 + | a . b |2 is equal to
A
72
B
64
C
48
D
36
2
NDA 2015 Paper 2
MCQ (Single Correct Answer)
+2.5
-0.83
Consider the following inequalities in respect of vectors a and b

1. | a + b | $$\le$$ | a | + | b |

2. | a $$-$$ b | $$\ge$$ | a | $$-$$ | b |

Which of the above is/are correct?
A
Only 1
B
Only 2
C
Both 1 and 2
D
Neither 1 nor 2
3
NDA 2015 Paper 2
MCQ (Single Correct Answer)
+2.5
-0.83
If the magnitude of difference of two unit vectors is $$\sqrt 3 $$, then the magnitude of sum of the two vectors is
A
$${1 \over 2}$$ unit
B
1 unit
C
2 units
D
3 units
4
NDA 2015 Paper 2
MCQ (Single Correct Answer)
+2.5
-0.83
If the vectors $$\alpha \widehat i + \alpha \widehat j + \gamma \widehat k$$, $$\widehat j + \widehat k$$ and $$\gamma \widehat i + \gamma \widehat j + \beta \widehat k$$ lie on a plane, where $$\alpha$$, $$\beta$$ and $$\gamma$$ are distinct non-negative numbers, then $$\gamma$$ is
A
arithmetic mean of $$\alpha$$ and $$\beta$$
B
geometric mean of $$\alpha$$ and $$\beta$$
C
harmonic mean of $$\alpha$$ and $$\beta$$
D
None of the above
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