$\"\"$

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The Trigonometric function is $\"\"$ .

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Find the real zeros of the function, by equating $\"\"$ on interval $\"\"$ .

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$\"\"$

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Apply double-angle formula: $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ .

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$\"\"$

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Solve $\"\"$ .

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$\"\"$ .

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The general solution of $\"\"$ is $\"\"$ , where $\"\"$ is any integer.

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$\"\"$

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For $\"\"$ , $\"\"$ .

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For $\"\"$ , $\"\"$ .

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Therefore, the solutions in the interval $\"\"$ are $\"\"$ .

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The real zeros of the function $\"\"$ are $\"\"$ .

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$\"\"$

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The real zeros of the function $\"\"$ are $\"\"$ .