$\"\"$

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From the diagram : a = 7, b = 3 and c = 8.

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Law of cosines for cos A : $\"\"$ .

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$\"\"$ (Substitute : a = 7, b = 3 and c = 8)

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$\"\"$ (Simplify)

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$\"\"$

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$\"\"$ (Simplify)

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

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Law of cosines for cos B : $\"\"$ .

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$\"\"$ (Substitute : a = 7, b = 3 and c = 8)

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$\"\"$ (Simplify)

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$\"\"$

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$\"\"$ (Simplify)

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

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Law of cosines for cos C : $\"\"$

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$\"\"$ (Substitute : a = 7, b = 3 and c = 8)

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$\"\"$ (Simplify)

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$\"\"$

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$\"\"$ (Simplify)

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

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The solution is $\"\"$ , $\"\"$ and $\"\"$ .