\"\"

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The function is \"\".

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Apply double angle formula : \"\".

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\"\"

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Maclaurin series of \"\":

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\"\"

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Then Maclaurin series of \"\" is

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\"\"

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\"\"

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\"\".\"\"

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Maclaurin series of \"\" is

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\"\"

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Maclaurin series of \"\" is \"\", \"\". \ \

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\"\"

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Maclaurin series of \"\" is \"\".