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

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$\"\"$

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$\"\"$

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Pythagorean identity : $\"\"$ .

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

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

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

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

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$\"\"$

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

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

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

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Solve the equation $\"\"$ .

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$\"\"$ ha no solutions.

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Solution set is $\"\"$ .

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$\"\"$ .