$\"\"$

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The expression is $\"\"$ .

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The power series of the sine function is $\"\"$ .

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The first four terms are $\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ .

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$\"\"$

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The power series of the cosine function is $\"\"$ .

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The first four terms are $\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ .

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

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$\"\"$

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$\"\"$

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$\"\"$ .

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$\"\"$ .

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The expected value is exactly $\"\"$ because $\"\"$ .

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$\"\"$

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$\"\"$ .