x_(C)=(-5+([red]2/1[/red])*1)/(1+([red]2/1[/red]))=(-3/3)=[b]-1[/b]
y_(C)=(-4+([red]2/1[/red])*5)/(1+([red]2/1[/red]))=(6/3)=[b]2[/b]
z_(C)=(-5+([red]2/1[/red])*7)/(1+([red]2/1[/red]))=(9)/3=[b]3[/b]
[m]ОС=\sqrt{(-1)^2+2^2+3^2}=\sqrt{14}[/m] - о т в е т