$\"\"$

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(a)

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The expression is $\"\"$ .

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Apply formula : $\"\"$

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$\"\"$

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Substitute the values : $\"\"$

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$\"\"$

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$\"\"$ \ \

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$\"\"$ \ \

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$\"\"$ .

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$\"\"$

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(b)

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The expression is $\"\"$ .

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Substitute the values : $\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ ( $\"\"$ ) $\"\"$

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(a) The exact value of the expression $\"\"$ is $\"\"$ .

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(b) The exact value of the expression $\"\"$ is 1.2071.