Question

Alguém me ajuda por favor

Answer 1

$\huge\boxed{\begin{array}{lr}13 {}^{2} = 5 {}^{2} + x {}^{2} \\ 169 = 25 + x {}^{2} \\ 169 - 25 = x {}^{2} \\ \sqrt{144} = \sqrt{x {}^{2} } \\ \boxed{x = \red{12}} \\ \\ \boxed{ \blue{a) \: 12}}\end{array}}$