\[\sqrt{7 - c} + \sqrt{c - 2} = 3\]
\[\left( \sqrt{7 - c} + \sqrt{c - 2} \right)^{2} = 9\]
\[5 + 2\sqrt{(7 - c)(c - 2)} = 9\]
\[2\sqrt{(7 - c)(c - 2)} = 4\]
\[\sqrt{(7 - c)(c - 2)} = 2.\]