If \(z\ne0\) is a complex number, then what is  equal to?

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NDA-I (Mathematics) Official Paper (Held On: 13 Apr, 2025)
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  1. 0
  2. π/2
  3. π
  4. 2π

Answer (Detailed Solution Below)

Option 1 : 0
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Detailed Solution

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Concept:

1. The amplitude (or argument) of a complex number \( z = r(\cos\theta + i\sin\theta) \) is given by \( \text{amp}(z) = \theta \).

2. The conjugate of \( z \), denoted as \( \overline{z} \), has an amplitude \( \text{amp}(\overline{z}) = -\theta \), because conjugating a complex number reflects it across the real axis in the Argand plane.

Formula Used:

\( \text{amp}(z) + \text{amp}(\overline{z}) = \theta + (-\theta) = 0 \).

Calculation:

\( z = r(\cos\theta + i\sin\theta) \)

\( \overline{z} = r(\cos\theta - i\sin\theta) \)

\( \text{amp}(z) + \text{amp}(\overline{z}) = \theta + (-\theta) = 0 \)

Conclusion:

\( \therefore \text{amp}(z) + \text{amp}(\overline{z}) = 0 \).

Hence, the correct answer is Option 1.

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