physics
posted by benjamin .
Vector A has a magnitude of 8.00 units and makes an angle of 45.0° with the positive xaxis. Vector B also has a magnitude of 8.00 units and is directed along the negative xaxis. Using graphical methods, find (a) the vector sum A + B and (b) the vector difference A – B.
Could someone please show me how this problem is done, maybe even with a graph somehow? Thanks

Vectors are directed. When the problem says " is directed along the negative x axis" IT DOES NOT MEAN that. It means the vector is in the same direction as the negative x axis.
Draw from the origin the A vector. At its tip,put a little arrow head. Now, in the DIRECTION of the negative x axis, from the tip of A, draw B.
A+B will then be the vector from the origin to the tip of B.
Now for AB. From the tip of A, draw B but in the direction of +x axis. From the origin to the tip of that reversed B is AB. 
See
http://i263.photobucket.com/albums/ii157/mathmate/VECTORS.jpg 
vecter a has a magnitude of 8.00 uints and makes an angle of 45.0with the positive xaxis?