1. Oct 19, 2005

### SS2006

when do i use
the

and when

THe Triangle law of vector addition

will they always give the same answer for vector a + vector b?
this is relaly confusing me thanks!

2. Oct 19, 2005

### TD

Last edited by a moderator: Apr 21, 2017
3. Oct 19, 2005

### SS2006

so u cant add using tirangle law
i heard it gives same result

4. Oct 19, 2005

### masudr

5. Oct 20, 2005

### TD

Substracting an opposite vector will gave the same result as adding it, of course.

Edit:
I think I know see what you mean. When two vectors have the same origin, you use the parallelogram rule.
Perhaps you're thinking of two vectors placed 'in serie', so one starts where the other ends. Then you can make the sum by contructing the triangle. The parallelogram rule will work here as well, by placing the second vector's tail where the first one starts.

Last edited: Oct 20, 2005
6. Oct 20, 2005

### HallsofIvy

Half of a parallelogram is a triangle- and since all the information given in the parallelogram is also present in the triangle you don't really need to draw the whole parallelogram. I think by "triangle law" you are simply referring to apply trigonometry (the sine and cosine laws in particular) to half the parallelogram.

7. Sep 11, 2011

### piyush3dxyz

hey will u please explain me the whole concept...becoz tmmorw is my physics test...
pls help...