$\"\"$

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The trigonometric identity is $\"\"$ .

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Consdier the left hand side $\"\"$ .

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Multiply numerator and denominator by $\"begin$ .

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$\"\"$

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Algebraic formula: $\"a$ .

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$\"equal$

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Apply Pythagorean identity: $\"Syntax$ .

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$\"\"$

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$\"\"$ .

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= Right hand side.

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

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$\"\"$ .