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If |omega|=1, then the set of points z=o...

If `|omega|=1`, then the set of points `z=omega+1/omega` is contained in or equal to the set of points z satisfying.

A

`"Re"(z) le 2` and `"Im"(z)=0`

B

`"Re"(z) le 1` and `"Im"(z)=0`

C

`|"Re"(z) le 2` and `"Im"(z)=0`

D

`|Re(z) le 1` and `"Im"(z)=0`

Text Solution

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The correct Answer is:
To solve the problem, we need to analyze the expression \( z = \omega + \frac{1}{\omega} \) given that \( |\omega| = 1 \). ### Step-by-Step Solution: 1. **Understanding the Condition**: Since \( |\omega| = 1 \), we can express \( \omega \) in terms of trigonometric functions. We can write: \[ \omega = e^{i\theta} = \cos\theta + i\sin\theta \] where \( \theta \) is a real number. 2. **Calculating \( \frac{1}{\omega} \)**: The reciprocal of \( \omega \) is: \[ \frac{1}{\omega} = \frac{1}{\cos\theta + i\sin\theta} \] To simplify this, we multiply the numerator and denominator by the conjugate: \[ \frac{1}{\omega} = \frac{\cos\theta - i\sin\theta}{\cos^2\theta + \sin^2\theta} = \cos\theta - i\sin\theta \] (since \( \cos^2\theta + \sin^2\theta = 1 \)). 3. **Substituting into \( z \)**: Now substitute \( \omega \) and \( \frac{1}{\omega} \) back into the expression for \( z \): \[ z = \omega + \frac{1}{\omega} = (\cos\theta + i\sin\theta) + (\cos\theta - i\sin\theta) \] Simplifying this gives: \[ z = 2\cos\theta \] The imaginary parts cancel out, leaving us with only the real part. 4. **Characterizing the Set of Points**: Since \( z = 2\cos\theta \), the real part of \( z \) can vary depending on \( \theta \). The maximum value of \( \cos\theta \) is 1 and the minimum value is -1. Therefore, the range of \( z \) is: \[ -2 \leq z \leq 2 \] This means that the real part of \( z \) is constrained to the interval \([-2, 2]\), and the imaginary part is always zero. 5. **Conclusion**: The set of points \( z = \omega + \frac{1}{\omega} \) is contained in the set of points satisfying: \[ \text{Re}(z) \leq 2 \quad \text{and} \quad \text{Im}(z) = 0 \] ### Final Answer: The set of points \( z = \omega + \frac{1}{\omega} \) is contained in or equal to the set of points satisfying: \[ \text{Re}(z) \leq 2 \quad \text{and} \quad \text{Im}(z) = 0 \]

To solve the problem, we need to analyze the expression \( z = \omega + \frac{1}{\omega} \) given that \( |\omega| = 1 \). ### Step-by-Step Solution: 1. **Understanding the Condition**: Since \( |\omega| = 1 \), we can express \( \omega \) in terms of trigonometric functions. We can write: \[ \omega = e^{i\theta} = \cos\theta + i\sin\theta ...
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OBJECTIVE RD SHARMA ENGLISH-COMPLEX NUMBERS -Section I - Solved Mcqs
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  2. If |omega|=2, then the set of points z=omega-1/omega is contained in o...

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  3. If |omega|=1, then the set of points z=omega+1/omega is contained in o...

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