$\"\"$

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The trigonometric equation is $\"\"$ .

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Rewrite the equation as $\"\"$ .

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Forward-inverse identities : $\"\"$ and $\"\"$ . .

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$\"\"$

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Squaring on each side.

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$\"\"$

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$\"\"$

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$\"\"$ .

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Solution of the equation is $\"\"$ is $\"\"$ .

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$\"\"$

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$\"\"$ .