1
NDA Mathematics 4 September 2022
MCQ (Single Correct Answer)
+2.5
-0.83
Change Language
Let z = $\frac{1+\text{i}\sin \theta}{1−\text{i}\sin \theta}$ where i = $\sqrt{−1}$

What is the modulus of z?

A
1
B
$\sqrt{2}$
C
1 + sin2 θ
D
$\frac{1+\sin^2\theta}{1−\sin^2\theta}$
2
NDA Mathematics 4 September 2022
MCQ (Single Correct Answer)
+2.5
-0.83
Change Language
Let z = $\frac{1+\text{i}\sin \theta}{1−\text{i}\sin \theta}$ where i = $\sqrt{−1}$

What is angle θ such that z is purely real ?

where n is an integer

A
$\frac{n\pi}{2}$
B
$\frac{(2n+1)\pi}{2}$
C
D
2nπ only
3
NDA Mathematics 4 September 2022
MCQ (Single Correct Answer)
+2.5
-0.83
Change Language
Let z = $\frac{1+\text{i}\sin \theta}{1−\text{i}\sin \theta}$ where i = $\sqrt{−1}$

What is angle θ such that z is purely imaginary ?

where n is an integer

A
$\frac{n\pi}{2}$
B
$\frac{(2n+1)\pi}{2}$
C
D
2nπ
4
NDA Mathematics 4 September 2022
MCQ (Single Correct Answer)
+2.5
-0.83
Change Language

Let P be the sum of first n positive terms of an increasing arithmetic progression A. Let Q be the sum of first n positive terms of another increasing arithmetic progression B.

Let P ∶ Q = (5n + 4) ∶ (9n + 6)

What is the ratio of the first term of A to that of B ?
A
1/3
B
2/5
C
3/4
D
3/5
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