Adding and subtracting 3 vectors?

Question

A - B + C = ?

here is the picture of the graph

http://farm4.static.flickr.com/3092/2807427904_2261044e2a_o.jpg

i get how to add and subtract 2 vectors but how do u do it with 3 vectors? My book doesnt show how...

the answer is 62.6 and 329 degree but i dont know how to get it

Answer 1

ok we got it!

x-axis means east

hint:  I'm rotating Counterclockwise

sum the x components:

44* Cos( 28)+ 26.5* Cos( 304)+ 31* Cos( 270) =53.668

sum the y components:

44* Sin( 28)+ 26.5* Sin( 304)+ 31* Sin( 270) =-32.313

Angle with the positive x-axis: =328.95 degrees

vector magnitude 62.64

The -B points B in the opposite direction

angle 270+(90-56)=270+34=304 degrees

How:

360+atn(y/x)*180/pi

=

360+atn(-32.313/53.668)*180/3.14159 = 328.95

The problem: your first yahoo question said:

B = 26.5, 56 degrees west of south

Your drawing shows 56 degrees "north of west"

Why:

atn(-32.313/53.668)*180

/3.14159 = -31.052 degrees below the +x-axis

This is the same as 360+(-31.052) CCW rotation

from the +x-axis.