$\"\"$

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The Trigonometric equation is $\"\"$ .

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$\"\"$

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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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$\"\"$

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$\"\"$

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$\"\"$

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Apply zero product property.

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

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$\"\"$

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Consider first part $\"\"$ .

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$\"\"$

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

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The solution is $\"\"$ .

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Substitute $\"\"$ in $\"\"$ , hence $\"\"$

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Substitute $\"\"$ in $\"\"$ , hence $\"\"$

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Substitute $\"\"$ in $\"\"$ , hence $\"\"$

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

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The solution set is $\"\"$ .

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$\"\"$

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Consider second part $\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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Apply zero product property.

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

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Consider $\"\"$ .

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$\"\"$

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

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

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The solution set is $\"\"$ .

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Consider $\"\"$

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$\"\"$

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$\"\"$

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The solution is $\"\"$ .

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The solution sets are $\"\"$ and $\"\"$

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The total set is $\"\"$ .

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$\"\"$

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For complete solution we need to combine above two solutions

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Combine solutions is $\"\"$ and $\"\"$ .

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Arrange in ascending order

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$\"\"$ .

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$\"\"$

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