# Help with Vector Proof

I have to prove that the projection of u onto v is equal to u dot v over the length of v squared, now if i rearrange the equation I get u dot v over the length of v times the unit vector in the direction of v but otherwise I am totally lost in proving this theorem.

Use Cauchy-Schwarz.

So I turn the u dot v into length of u times length of v and set the expression into an inequality?

[quote]JoabSonOfZeruiah wrote:
So I turn the u dot v into length of u times length of v and set the expression into an inequality?[/quote]

Sorry, I was being obtuse, you use it to get the angle between two vectors. Hopefully that allows you to make some progress.

[quote]Rational Gaze wrote:

[quote]JoabSonOfZeruiah wrote:
So I turn the u dot v into length of u times length of v and set the expression into an inequality?[/quote]

Sorry, I was being obtuse, you use it to get the angle between two vectors. Hopefully that allows you to make some progress.[/quote]
lol nice joke, Ill see how far ill get in a while.