Step-by-step explanation:
[tex] {c}^{2} = {a}^{2} + {b}^{2} \\ {c}^{2} = {15}^{2} + {15}^{2} \\ {c}^{2} = 450 \\ c = \sqrt{450} = \sqrt{ {15}^{2} \times 2 } = 15 \sqrt{2} [/tex]
