[tex]Zadanie\\\\A=(1,1)\ ;\ B=(5,4)\\\\\mid AB\mid=\sqrt{(x_B-x_A)^2+(y_B-y_A)^2}\\\\\mid AB\mid= \sqrt{(5-1)^2+(4-1)^2}=\sqrt{4^2+3^2}=\sqrt{16+9}=\sqrt{25}=5\ (j)[/tex]
