How to prove $F(x,y)=(x^2+y^2)^{1/2}$ is continuous in $\Bbb{R}^2$?

How to prove $F(x,y)=(x^2+y^2)^{1/2}$ is continuous in $\Bbb{R}^2$?

Please, I need the continuity demonstration of the function $F(x,y)=
(x^2+y^2)^{1/2}$. Thanks!