We have three vectors, a = (1,2,3) b = (2,-1,x) c = (y,z,1). We need to find x, y and z, if the vectors are right-angled.

I am trying to solve it with the dot product. I know that the dot product of two vectors is equal to zero, if they are right-angled.

But i always get x = 0, y = 0, z = 0.

and sorry for no arrows, i have to learn Latex, i know.