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All possible values of theta in [0, 2pi]...

All possible values of `theta in [0, 2pi]` for which `sin 2theta +tan 2theta gt 0` lie in :

A

`(0, (pi)/(2)) cup (pi, (3pi)/(2))`

B

`(0, (pi)/(2)) cup ((pi)/(2), (3pi)/(4)) cup (pi, (7pi)/(6))`

C

`(0, (pi)/(4)) cup ((pi)/(2), (3pi)/(4)) cup ((3pi)/(2), (11pi)/(6))`

D

`(0, (pi)/(4)) cup ((pi)/(2), (3pi)/(4)) cup (pi, (5pi)/(4)) cup ((3)/(2), (7pi)/(4))`

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To solve the inequality \( \sin 2\theta + \tan 2\theta > 0 \) for \( \theta \) in the interval \( [0, 2\pi] \), we can follow these steps: ### Step 1: Rewrite the inequality We know that \( \tan 2\theta = \frac{\sin 2\theta}{\cos 2\theta} \). Therefore, we can rewrite the inequality as: \[ \sin 2\theta + \frac{\sin 2\theta}{\cos 2\theta} > 0 \] This simplifies to: \[ \sin 2\theta \left(1 + \frac{1}{\cos 2\theta}\right) > 0 \] or equivalently: \[ \sin 2\theta \cdot \frac{1 + \cos 2\theta}{\cos 2\theta} > 0 \] ### Step 2: Analyze the factors The inequality can be analyzed by considering the signs of each factor: 1. \( \sin 2\theta > 0 \) 2. \( 1 + \cos 2\theta > 0 \) (which is always true since \( \cos 2\theta \) ranges from -1 to 1) 3. \( \cos 2\theta > 0 \) ### Step 3: Solve \( \sin 2\theta > 0 \) The sine function is positive in the intervals: \[ 2\theta \in (0, \pi) \cup (2\pi, 3\pi) \] Dividing by 2 gives: \[ \theta \in (0, \frac{\pi}{2}) \cup (\pi, \frac{3\pi}{2}) \] ### Step 4: Solve \( \cos 2\theta > 0 \) The cosine function is positive in the intervals: \[ 2\theta \in (-\frac{\pi}{2}, \frac{\pi}{2}) \cup (\frac{3\pi}{2}, \frac{5\pi}{2}) \] Dividing by 2 gives: \[ \theta \in (-\frac{\pi}{4}, \frac{\pi}{4}) \cup (\frac{3\pi}{4}, \frac{5\pi}{4}) \] ### Step 5: Find the intersection of the intervals Now we need to find the intersection of the intervals from steps 3 and 4: 1. From \( \sin 2\theta > 0 \): \( (0, \frac{\pi}{2}) \cup (\pi, \frac{3\pi}{2}) \) 2. From \( \cos 2\theta > 0 \): \( (-\frac{\pi}{4}, \frac{\pi}{4}) \cup (\frac{3\pi}{4}, \frac{5\pi}{4}) \) The intersections are: - For \( (0, \frac{\pi}{2}) \) and \( (-\frac{\pi}{4}, \frac{\pi}{4}) \): The intersection is \( (0, \frac{\pi}{4}) \). - For \( (\pi, \frac{3\pi}{2}) \) and \( (\frac{3\pi}{4}, \frac{5\pi}{4}) \): The intersection is \( (\frac{3\pi}{4}, \frac{5\pi}{4}) \). ### Step 6: Combine the results Thus, the solution for \( \theta \) in the interval \( [0, 2\pi] \) is: \[ \theta \in (0, \frac{\pi}{4}) \cup (\frac{3\pi}{4}, \frac{5\pi}{4}) \] ### Final Answer The possible values of \( \theta \) for which \( \sin 2\theta + \tan 2\theta > 0 \) lie in: \[ (0, \frac{\pi}{4}) \cup (\frac{3\pi}{4}, \frac{5\pi}{4}) \]
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