Respuesta :

Answer:

7

Step-by-step explanation:

apply the Pythagorean theorem

[tex]10 {}^{2} = ( \sqrt{51} ) {}^{2} + x {}^{2} \\ 100 = 51 + x {}^{2} \\ 100 - 51 = x {}^{2} \\ 49 = x {}^{2} \\ x = 7[/tex]