Good day folks,

Just doing some reading about cartesian dot product etc.

I realise i x j = k, i x i = 0 etc.

Can someone tell me if there are relations for i + i and i/i ?

I apologise - I am a bit rusty with this stuff...

Kind regards.

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- Aug 20th 2011, 04:43 PMpaulbk108Vectors: i + i = ?
Good day folks,

Just doing some reading about cartesian dot product etc.

I realise i x j = k, i x i = 0 etc.

Can someone tell me if there are relations for i + i and i/i ?

I apologise - I am a bit rusty with this stuff...

Kind regards. - Aug 20th 2011, 04:47 PMmr fantasticRe: Cartesian co-ordinates i + i = ?
- Aug 20th 2011, 05:10 PMpaulbk108Re: Cartesian co-ordinates i + i = ?
Very good. Thank you. Simple.

What about i + j = ? Or is that not defined as well?

Regards. - Aug 20th 2011, 05:16 PMpaulbk108Re: Cartesian co-ordinates i + i = ?
Th reason I ask:

I have an example here that goes from

1.2i + 1.2j + 0.7i + 0.7j

= 1.2 + 0.7

I just can't figure out why...

Regards. - Aug 20th 2011, 05:35 PMPlatoRe: Cartesian co-ordinates i + i = ?
- Aug 20th 2011, 05:48 PMpaulbk108Re: Cartesian co-ordinates i + i = ?
I have

-(Vc)i = -1.2i + 1.2j + 0.7(Vc)i + 0.7(Vc)j

=> -(Vc) = -1.2 + 0.7(Vc)

Not sure if that makes a difference. - Aug 20th 2011, 06:33 PMskeeterRe: Cartesian co-ordinates i + i = ?
- Aug 20th 2011, 07:12 PMpaulbk108Re: Cartesian co-ordinates i + i = ?
Solving for Vca.

-Vci = (3k) x (0.4i + 0.4j) + ((Vca)cos45i + (Vca)sin45j)

=> -Vci = -1.2i + 1.2j +0.7(Vca)i + 0.7(Vca)j

=> -Vc = -1.2 + 0.7(Vca)

=> 0 = 1.2 + 0.7(Vca)

=> Vca = -1.697 m/s

=> Vc = 2.4 m/s.

I hope that clears it up. I also hope you can assist me further...

Regards. - Aug 20th 2011, 07:36 PMskeeterRe: Cartesian co-ordinates i + i = ?
to tell you the honest truth, this makes absolutely no mathematical sense to me.

is that a cross product at the start?. what does "k" represent?

why don't you "copy" the original problem, upload it to imageshack, and post it as a link so that someone can make sense of it? - Aug 20th 2011, 08:09 PMpaulbk108Re: Cartesian co-ordinates i + i = ?
Attached is the solution in question. Hope now it is a bit clearer.

Regards. - Aug 20th 2011, 08:11 PMSammySRe: Cartesian co-ordinates i + i = ?