Dude, it's a triangle.

Take a 2-D graph, X, Y coords.

Start at (0,0)
Put one vector end there, follow the magnitude out at the appropriate angle.
Affix the second vector to the tip of the previous.
The vector that connects the origin (0,0) to the tip of the second vector is the resultant (AKA A+B)

It's just a triangle...You can do trig, right???

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1982 240D, sold 9/17/2008
1987 300D TurboW124.133 - 603.960, 722.317 - Smoke Silver Metallic / Medium Red (702/177), acquired 8/15/2009
262,715 and counting