Find the unit vector perpendicular to each of the vectors 2i+j+k and i-j+2k?

1 answer

does "cross product" or "vector product" ring a bell?
the cross product of two vectors is perpendicular to both

+i +j +k
+2 +1 +1
+1 -1 +2

(2+1)i +(1-4)j + (-2-1)k

= 3i -3j -3 k