Question

Find all points on the y-axis that are a distance 6 from p(4, 7).

Answer 1

$\sqrt{16 + {(7 - y)}^{2} } = 6 \\ 16 + {(7 - y)}^{2} = 36 \\ {(7 - y)}^{2} = 20$
$7 - y = \sqrt{20} > > y = 7 - \sqrt{20} \\ 7 - y = - \sqrt{20} > > y = 7 + \sqrt{20}$