$\"\"$

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The trigonometric equation is $\"\"$ and the interval is $\"\"$ .

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$\"\"$ .

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$\"\"$ .

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$\"\"$ .

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$\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$ .

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$\"\"$ and $\"\"$ .

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$\"\"$

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Solve $\"\"$ .

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The function $\"\"$ is negative in third and fourth quadrants.

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$\"\"$ .

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$\"\"$ .

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The solutions in the interval $\"\"$ are $\"\"$ .

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$\"\"$

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Solve $\"\"$ .

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The function $\"\"$ is positive in first and second quadrants.

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$\"\"$ .

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$\"\"$ .

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The solutions in the interval $\"\"$ are $\"\"$ .

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$\"\"$

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The solution set for $\"\"$ is $\"\"$ .