5)C(0;y;0); A(2;-1;3);B(3;-2;1)
AC=CB
AC^2=CB^2
AC^2=(0-2)^2+(y+1)^2+(0-3)^2=4+y^2+2y+1+9=y^2+2y+14
BC^2=(0-3)^2+(y+2)^2+(0-1)^2=9+y^2+4y+4+1=y^2+4y+14
y^2+2y+14=y^2+4y+14
y=0
C(0;0;0)
AC=√14;BC=√14
AB^2=(2-3)^2+(-1+2)^2+(3-1)^2=6; AB=√6
5)C(0;y;0); A(2;-1;3);B(3;-2;1)
AC=CB
AC^2=CB^2
AC^2=(0-2)^2+(y+1)^2+(0-3)^2=4+y^2+2y+1+9=y^2+2y+14
BC^2=(0-3)^2+(y+2)^2+(0-1)^2=9+y^2+4y+4+1=y^2+4y+14
y^2+2y+14=y^2+4y+14
y=0
C(0;0;0)
AC=√14;BC=√14
AB^2=(2-3)^2+(-1+2)^2+(3-1)^2=6; AB=√6