Cross and Dot products

[ballaholic8]

HEy guys i have a previous years test that im reviewing for my calculus and vectors class. i cant seem to figure out this question. can someone please help me. thanks alot

 

[mmm4444bot]

WHY are you having trouble figuring out the question?

Is the notation an issue? Are there any symbols that you do not understand?

Do you know anything about vectors?

Do you know anything about dot products?

Unless you first give me a clue as to why you are stuck and what you already know, I'm not interested in guessing at what kind of help to provide.

Also, please read the post titled, "Read Before Posting", if you have not already done so.

Cheers,

~ Mark

 

[ballaholic8]

i understand dot product and cross product. but the problem im having is how to tackle a question like this. the steps i need to take to reach the answer. and wheather or not if im guessing u,v and w or setting up equations to figure it out.

 

[mmm4444bot]

i understand dot product and cross product. but the problem im having is how to tackle a question like this ...

Perhaps, you need to understand some properties.

When you cross two vectors, the resulting vector is perpendicular to the plane which contains the other two.

The cross product of two parallel vectors is the zero vector.

If the dot product of two vectors is zero, then those two vectors are perpendicular.

This is enough to reason out the final dot product in your exercise.

For example, since we're told that u dotted with the cross of v and w equals zero, we know that u must be parallel to the plane which contains both v and w. In fact, u must be contained within this plane, too, since the two vectors are positioned in a dot product so that their tails meet.

Continue with this type of reasoning.

Let us know if you need more help; please explain your reasoning thus far.

Cheers,

~ Mark



MY EDIT: Finished what I started to say (Thanks, Subhotosh)

 

[Deleted member 4993]

HEy guys i have a previous years test that im reviewing for my calculus and vectors class. i cant seem to figure out this question. can someone please help me. thanks alot

Hint:

If u•vxw = 0

then u, v and w are co-planar.