Use the Pythagorean theorem for the right triangle [tex]ABC,[/tex] where
[tex]AB[/tex] is the hypotenuse of the triangle;
[tex]AC[/tex] and [tex]BC[/tex] are the other two sides.
So,
[tex](AC)^{2}+(BC)^{2}=(AB)^{2}\\\\ 7^{2}+10^{2}=(AB)^{2}\\\\ (AB)^{2}=49+100\\\\ (AB)^{2}=149\\\\ AB=\sqrt{149}[/tex]
