Answer:
3√6
Step-by-step explanation:
[tex] {a}^{2} = {b}^{2} + {c}^{2} [/tex]
[tex] = {1}^{2} + {( \sqrt{53} )}^{2} [/tex]
[tex] = 1 + 53[/tex]
[tex] {a}^{2} = 54[/tex]
[tex]a = \sqrt{54} = 3 \sqrt{6} [/tex]
