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If |omega|=2, then the set of points z=o...

If `|omega|=2`, then the set of points `z=omega-1/omega` is contained in or equal to the set of points z satisfying

A

`"Im"(z)=0`

B

`|"Im"(z)| le 1`

C

`|"Re"(z)| le 2`

D

`|z| le 3`

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The correct Answer is:
To solve the problem, we need to find the set of points \( z = \omega - \frac{1}{\omega} \) given that \( |\omega| = 2 \). ### Step-by-Step Solution: 1. **Express \( \omega \)**: Since \( |\omega| = 2 \), we can express \( \omega \) in polar form: \[ \omega = 2(\cos \theta + i \sin \theta) = 2e^{i\theta} \] 2. **Calculate \( \frac{1}{\omega} \)**: The reciprocal of \( \omega \) is given by: \[ \frac{1}{\omega} = \frac{1}{2(\cos \theta + i \sin \theta)} = \frac{1}{2}(\cos(-\theta) + i \sin(-\theta)) = \frac{1}{2}(\cos \theta - i \sin \theta) \] 3. **Substitute into \( z \)**: Now substitute \( \omega \) and \( \frac{1}{\omega} \) into the expression for \( z \): \[ z = \omega - \frac{1}{\omega} = 2(\cos \theta + i \sin \theta) - \frac{1}{2}(\cos \theta - i \sin \theta) \] 4. **Combine the terms**: Simplifying the expression for \( z \): \[ z = 2\cos \theta + 2i\sin \theta - \frac{1}{2}\cos \theta + \frac{1}{2}i\sin \theta \] \[ z = \left(2 - \frac{1}{2}\right)\cos \theta + \left(2 + \frac{1}{2}\right)i\sin \theta \] \[ z = \frac{3}{2}\cos \theta + \frac{5}{2}i\sin \theta \] 5. **Find the modulus of \( z \)**: The modulus of \( z \) is given by: \[ |z| = \sqrt{\left(\frac{3}{2}\cos \theta\right)^2 + \left(\frac{5}{2}\sin \theta\right)^2} \] \[ |z| = \sqrt{\frac{9}{4}\cos^2 \theta + \frac{25}{4}\sin^2 \theta} \] \[ |z| = \frac{1}{2}\sqrt{9\cos^2 \theta + 25\sin^2 \theta} \] 6. **Analyze the maximum value of \( |z| \)**: To find the maximum value of \( |z| \), we can express it as: \[ |z| = \frac{1}{2}\sqrt{9\cos^2 \theta + 25\sin^2 \theta} \] We can use the Cauchy-Schwarz inequality or analyze the expression directly. The maximum occurs when \( \sin^2 \theta \) and \( \cos^2 \theta \) take on values that maximize the expression. The maximum value of \( |z| \) can be calculated as: \[ |z| \leq \frac{1}{2} \sqrt{9 + 25} = \frac{1}{2} \sqrt{34} \] Since \( \sqrt{34} \approx 5.83 \), we find: \[ |z| \leq \frac{5.83}{2} \approx 2.915 \] Thus, we conclude: \[ |z| \leq 3 \] ### Conclusion: The set of points \( z = \omega - \frac{1}{\omega} \) is contained in or equal to the set of points satisfying \( |z| \leq 3 \).

To solve the problem, we need to find the set of points \( z = \omega - \frac{1}{\omega} \) given that \( |\omega| = 2 \). ### Step-by-Step Solution: 1. **Express \( \omega \)**: Since \( |\omega| = 2 \), we can express \( \omega \) in polar form: \[ \omega = 2(\cos \theta + i \sin \theta) = 2e^{i\theta} ...
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