# Parallel and Perpendicular Vectors

• Nov 17th 2011, 12:03 PM
benny92000
Parallel and Perpendicular Vectors
To find parallel vector, divide by norm.
Perpendicular vectors: dot product equals 0

That is what I know about parallel and perpendicular vectors. Can someone make a quick sample problem to apply these principles? (I know what norm and dot product are)
• Nov 17th 2011, 12:50 PM
HallsofIvy
Re: Parallel and Perpendicular Vectors
You can find a [b]unit[b] vector (norm= 1) parallel to a given vector by dividing by the norm. Multiplying a given vector by any number will give a parallel vector. Yes, two vectors are perpendicular if and only if their dot product is 0.

Okay: find a unit vector parallel to the vector 2i+ 3j- 4k. Find a vector parallel to 2i+ 3j- 4k that has length twice as long!

Relatively easy problem, find a vector, in the xy-plane, perpendicular to 3i+ 4j. Slightly harder, find a vector perpendicular to 4i- 3j+ 2k.
• Nov 25th 2011, 12:32 PM
benny92000
Re: Parallel and Perpendicular Vectors
Thank you. Had to revisit what you told me :)