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The equation is $\"\"$ on $\"\"$ .

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Pythagorean identity: $\"\"$ .

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Substitute $\"\"$ in above expression.

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$\"\"$

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

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Solve the equation $\"\"$ .

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

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

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$\"\"$ .

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

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$\"\"$ .

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Solution for $\"\"$ in the interval $\"\"$ , then $\"\"$ .

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Solve the equation $\"\"$ .

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$\"\"$

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

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

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$\"\"$ .

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

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$\"\"$ .

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Solution for $\"\"$ in the interval $\"\"$ , then $\"\"$ .

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Solution set is $\"\"$ .

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$\"\"$ .