\"\"

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The lengths of two sides of a right triangle are \"\".

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To find: side a.

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Apply Pythagorean theorem: \"a

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\"\"                            (Substitute 77 for b and 85 for c)

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\"\"                      (Evaluate powers: \"\")\"\"

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\"\"  (Subtract 5929 from each side)

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

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 \"\"                           (Take square root to each side)

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\"\"                               (Write \"\")

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\"\"                                         (Cancel square and root)\"\"

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The length of the third side \"\".