[tex]y {}^{2} + 3 {}^{2} = 5 {}^{2} [/tex]
[tex]y {}^{2} = 25 - 9 = 16[/tex]
[tex]y = \sqrt{16} = 4[/tex]
(Y is the missing line of the triangle on the left)
[tex]x ^{2} = {y}^{2} + 7 {}^{2} [/tex]
[tex]x {}^{2} = 4 {}^{2} + 7 {}^{2} [/tex]
[tex]x {}^{2} = 16 + 49[/tex]
[tex]x {}^{2} = 65[/tex]
[tex]x = \sqrt{65} [/tex]
