[tex]\bf \textit{using the pythagorean theorem}\\\\
c^2=a^2+b^2\qquad
\begin{cases}
c=hypotenuse\\
a=adjacent\\
b=opposite\\
-------\\
c=x\\
a=7\\
b=10
\end{cases}\implies x^2=7^2+10^2
\\\\\\
x=\sqrt{7^2+10^2}[/tex]
and surely you know how much that is.
