$\"\"$

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The equation is $\"\"$ .

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Double angle formula : $\"\"$ .

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$\"\"$

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$\"\"$

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First solve $\"\"$ .

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$\"\"$ .

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

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The solution is $\"\"$ .

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If $\"\"$ , then $\"\"$ .

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If $\"\"$ , then $\"\"$ .

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$\"\"$

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Solve $\"\"$ .

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$\"\"$ .

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

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The solution is $\"\"$ .

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If $\"\"$ , then $\"\"$ .

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If $\"\"$ , then $\"\"$ .

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The solutions of the equation are $\"\"$ , $\"\"$ , $\"\"$ ,

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and $\"\"$ in the interval $\"\"$ . $\"\"$

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The solutions of the equation are $\"\"$ , $\"\"$ , $\"\"$ ,

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and $\"\"$ in the interval $\"\"$ .

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