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The trigonometric equation is $\"\"$ .

Pythagorean identity : $\"\"$ .

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$\"\"$ .

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Solve the equation $\"\"$ .

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The general solution of $\"\"$ is $\"\"$ .

Where $\"\"$ .

Substitute $\"\"$ in $\"\"$ .

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Solution for $\"\"$ in the interval $\"\"$ is $\"\"$ .

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Solution for $\"\"$ in the interval $\"\"$ is $\"\"$ .