Use the cross product to find a parallel vector I'm confused by this exercise here :
Using the cross product, for which value(s) of t the vectors w(1,t,-2) and r(-3,1,6) will be parallel
I know that if I use the cross product of two vectors, I will get a resulting perpenticular vector. However, how to you find a parallel vector? 
Thanks for your help

v1(1,t,-2); v2(-3,1,6); 3*v1 is parallel to v2 if t=-1/3
Also: Perform vector Cross Product v1Xv2=v3 to get components:
v3((6*t+2),(6-6),(1+3*y)); the cross product is 0 when t=-1/3
