# Length of a vector

• November 4th 2009, 03:43 AM
El Sparko
Length of a vector
Hi Math help Forum

I'm not sure if this is the right thread to be posting this in, so sorry.

the question is to calculate |a x b| where

a= i+j-k
b=2i-j+3k

I've worked out a x b to be 2i - 5j - 3k , but I'm not really sure as to where to go from here.

any help would be great

Thanks

ES
• November 4th 2009, 04:04 AM
earboth
Quote:

Originally Posted by El Sparko
Hi Math help Forum

I'm not sure if this is the right thread to be posting this in, so sorry.

the question is to calculate |a x b| where

a= i+j-k
b=2i-j+3k

I've worked out a x b to be 2i - 5j - 3k , but I'm not really sure as to where to go from here.

any help would be great

Thanks

ES

Calculate now the length (or the absolute value) of (2, -5, -3).

You should get the result $|\vec v| = \sqrt{38}$