Posted by ODU on .
Vector A has a magnitude of 71 units and points due west, while vector B has the same magnitude and points due south. Find the magnitude and direction of (a) A + B and (b) A  B . Specify the directions relative to due west.

gen physics 
Henry,
A = 71[180o]. B = 71[270o].
a. A+B=(71*cos180+71*cos270)+i(71*sin180+71*sin270)
A+B = (71+0) + i(071)
A+B = 71  i71 = 100.4]45o] or
100.4[45o+180o] = 100.4[225o].
Since the resultant is in Q3, 45o is the
reference angle.
b. AB=(71*cos18071*cos270)i(71sin18071sin270)
AB = (710) + i(0(71))
AB = 71 + i71 = 100.4[45o] or
100.4[45+180] = 100.4[135o]. 
gen physics 
Anonymous,
A force F1of magnitude 5.00 units acts on an object at the origin in a direction è = 45.0° above the positive xaxis. (See the figure below.) A second force F2of magnitude 5.00 units acts on the object in the direction of the positive yaxis. Find graphically the magnitude and direction of the resultant force F1 + F2.
magnitude
1 units
direction
2° counterclockwise from the +xaxis