$\"\"$

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The expression is $\"\"$ .

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Rewrite the expression

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$\"\"$ .

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Consider $\"\"$ then $\"\"$ .

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The expression can be written as $\"\"$

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$\"\"$

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Here $\"\"$ and $\"\"$ .

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Pythagoras rule : $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$ .

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Therefore $\"\"$ .

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Hence $\"\"$ .

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$\"\"$

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Substitute $\"\"$ in the expression $\"\"$ .

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The expression is $\"\"$

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Property of inverse trigonometry functions : $\"\"$ .

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$\"\"$ $\"\"$

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

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$\"\"$

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