$\"\"$

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Let $\"\"$ and $\"\"$ .

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Find $\"\"$ and $\"\"$ first.

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$\"\"$ (Apply Secant theorem)

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

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$\"\"$ (Substitute $\"\"$ and $\"\"$ )

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$\"\"$ (Add: $\"\"$ )

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$\"\"$ (Subtract: $\"\"$ )

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$\"\"$ (Divide: $\"\"$ ) $\"\"$

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The value of $\"\"$ .