Comprehension

Let z =  where i = 

What is angle θ such that z is purely real ?

where n is an integer

This question was previously asked in
NDA 02/2022 Mathematics Official Paper (Held On 04 Sep 2022)
View all NDA Papers >
  1. 2nπ only

Answer (Detailed Solution Below)

Option 3 : nπ
Free
NDA 01/2025: English Subject Test
30 Qs. 120 Marks 30 Mins

Detailed Solution

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Concept:

If z = x + iy is purely real, then y = 0

Calculation:

Given, 

z =  where i = 

Multiply numerator and denominator by (1 + i sin θ) 

Since z is purely real,

⇒ 

⇒ sin θ = 0

⇒ θ = nπ 

∴ The correct answer is option (3).

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