[tex]a \: \: \sqrt{ {82}^{2} - 18 {}^{2} } = \sqrt{6724 - 324 } = \sqrt{6400} = 80 \\ \\ b \sqrt{65 {}^{2} - 63 {}^{2} } = \sqrt{4225 - 3969} = \sqrt{256} = 16[/tex]
