NDA & NA Exam (I)- 2016 - Mathematics Defence Question Paper

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NDA & NA Exam (I)- 2016 - Mathematics

NDA & NA Exam (I)- 2016 - Mathematics Defence Questions

1.
Suppose \( \omega \) is a cube root of unity with \( \omega \neq 1 \). Suppose P and Q are the points on the complex plane defined by \( \omega \) and \( \omega^{2} \). If O is the origin, then what is the angle between OP and OQ?
A.
\( 60^{\circ} \)
B.
\( 90^{\circ} \)
C.
\( 120^{\circ} \)
D.
\( 150^{\circ} \)
ANSWER :
C. \( 120^{\circ} \)
2.
Suppose there is a relation * between the positive numbers x and y given by x * y if and only if \( x \leq y^{2} \). Then which one of the following is correct?
A.
* is reflexive but not transitive and symmetric
B.
* is transitive but not reflexive and symmetric
C.
* is symmetric and reflexive but not transitive
D.
* is neither reflexive, nor symmetric, nor transitive
ANSWER :
D. * is neither reflexive, nor symmetric, nor transitive
3.
If \( x^{2} - px + 4 > 0 \) for all real values of x, then which one of the following is correct?
A.
\( |p| < 4 \)
B.
\( |p| \leq 4 \)
C.
\( |p| > 4 \)
D.
\( |p| \geq 4 \)
ANSWER :
A. \( |p| < 4 \)
4.
If \( z = x + iy = \left(\frac{1}{\sqrt{2}} - \frac{i}{\sqrt{2}}\right)^{-25} \), where \( i = \sqrt{-1} \), then what is the fundamental amplitude of \( \frac{z - \sqrt{2}}{z - i\sqrt{2}} \)?
A.
\( \pi \)
B.
\( \frac{\pi}{2} \)
C.
\( \frac{\pi}{3} \)
D.
\( \frac{\pi}{4} \)
ANSWER :
A. \( \pi \)
5.
If \( f(x_{1}) - f(x_{2}) = f\left(\frac{x_{1} - x_{2}}{1 - x_{1}x_{2}}\right) \) for \( x_{1}, x_{2} \in (-1, 1) \), then what is f(x) equal to?
A.
\( \ln\left(\frac{1-x}{1+x}\right) \)
B.
\( \ln\left(\frac{2+x}{1-x}\right) \)
C.
\( \tan^{-1}\left(\frac{1-x}{1+x}\right) \)
D.
\( \tan^{-1}\left(\frac{1+x}{1-x}\right) \)
ANSWER :
A. \( \ln\left(\frac{1-x}{1+x}\right) \)
6.
What is the range of the function \( y = \frac{x^{2}}{1+x^{2}} \) where \( x \in R \)?
A.
[0, 1)
B.
[0, 1]
C.
(0, 1)
D.
(0, 1]
ANSWER :
A. [0, 1)
7.
A straight line intersects x and y axes at P and Q respectively. If (3, 5) is the middle point of PQ, then what is the area of the triangle OPQ?
A.
12 square units
B.
15 square units
C.
20 square units
D.
30 square units
ANSWER :
D. 30 square units
8.
If a circle of radius b units with centre at (0, b) touches the line \( y = x - \sqrt{2} \), then what is the value of b?
A.
\( 2 + \sqrt{2} \)
B.
\( 2 - \sqrt{2} \)
C.
\( 2\sqrt{2} \)
D.
\( \sqrt{2} \)
ANSWER :
A. \( 2 + \sqrt{2} \)
9.
For the next three (3) items that follow:
Consider the function \( f(\theta) = 4(\sin^{2}\theta + \cos^{4}\theta) \).

What is the maximum value of the function \( f(\theta) \)?
A.
1
B.
2
C.
3
D.
4
ANSWER :
D. 4
10.
What is the minimum value of the function \( f(\theta) \)?
A.
0
B.
1
C.
2
D.
3
ANSWER :
D. 3