# Dot or Cross product?

• Apr 24th 2008, 12:29 PM
MilK
Dot or Cross product?
If i need to find the angle between two vectors a, b, which method should i use? dot or cross product?

And in when do i use dot/cross product to find the angle?
• Apr 24th 2008, 12:32 PM
Moo
Hello,

The dot product uses the cosine of the angle between the vectors and the cross product uses the sine of the angle :)
So it depends/
• Apr 24th 2008, 12:35 PM
Isomorphism
Quote:

Originally Posted by MilK
If i need to find the angle between two vectors a, b, which method should i use? dot or cross product?

Well,given a choice, I'd prefer dot product. Computing it is simpler :D.
• Apr 24th 2008, 12:41 PM
Moo
Quote:

Originally Posted by Isomorphism
Well,given a choice, I'd prefer dot product. Computing it is simpler :D.

Plus, dot product can be used in 2D space, not cross product :D
• Apr 25th 2008, 12:16 AM
MilK
so if i want to find the angle, i can use either dot or cross product? which will give me the same result?
• Apr 25th 2008, 12:18 AM
o_O
Yes although I agree that using the dot product would in general be more easier. If you were given two vectors, would you rather find their scalar or cross product?
• Apr 25th 2008, 12:30 AM
MilK
of cos dot(Nod)