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The trigonometric expression is $\"\"$ .

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Let $\"\"$ in the interval $\"\"$ .

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$\"\"$ .

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From Pythagorean theorem,

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The square of the hypotenuse is equal to sum the squares of the other two sides.

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$\"\"$

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$\"\"$ .

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$\"\"$ .

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Let $\"\"$ in the interval $\"\"$ .

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$\"\"$ .

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From Pythagorean theorem,

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The square of the hypotenuse is equal to sum the squares of the other two sides.

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$\"\"$

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$\"\"$ .

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Substitute $\"\"$ and $\"\"$ in trigonometric expression.

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$\"\"$ .

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Subtraction formula for sine function: $\"\"$ .

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$\"\"$

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Substitute these values $\"\"$ in above expression.

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$\"\"$

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$\"\"$ .

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The algebraic expression for $\"\"$ is $\"\"$ ,

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