\"\"

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The trigonometric function is \"\".

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From the diagram : opposite side = 8 and adjacent side = 15.

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Pythagorean theorem : \"\".

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\"\"

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\"\"

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\"\".

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\"\", and

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 \"\".\"\"

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\"\"            (Apply half angle formula: \"\")

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\"\"          (Simplify)

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\"\"         (Simplify)\"\"

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The exact value of \"\" is \"\".