Understanding Vector Addition with the Parallelogram and Triangle Laws

[SS2006]

when do i use
the
Paralleogram Law of Vector Addition

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!

 

[TD]

Adding two vectors will require the parallelogram rule. If you'd want to substract to vectors, you can either use the triangle rule or again the parallelogram rule, but then adding the opposite vector.

Check http://en.wikipedia.org/wiki/Vector_(spatial)#Vector_addition_and_subtraction"

 

[SS2006]

so u can't add using tirangle law
i heard it gives same result

 

[masudr]

Just add the components!

 

[TD]

so u can't add using tirangle law
i heard it gives same result

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.

 

[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.

 

[piyush3dxyz]

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.

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