Physics- Bet No One Can Do It?

Question

For the vectors given in Fig. 3-32 (|A| = 60.0 and = 60.0°), determine the following.

Figure 3-32
http://www.webassign.net/giancoli5/3_35alt.gif

(a) A - B + C
Magnitude:___
Direction:___ ° (counterclockwise from the +x axis is positive)
(b) A + B - C
Magnitude:___
Direction:___ ° (counterclockwise from the +x axis is positive)
(c) C - A - B
Magnitude:___
Direction:___ ° (counterclockwise from the +x axis is positive)

Answer 1

Easy, but boring, so I don't know if anyone will *want* to do it.

Resolve A, B, C into components:
A = (60.0 cos 28.0°, 60.0 sin 28.0°) = (52.98, 28.17)
B = (-40.0 cos 60.0°, 40.0 sin 60.0°) = (-20.00, 34.64)
C = (0, -46.8)

Then we get
A - B + C = (72.98, -53.27)
Magnitude 90.4, direction -36.1° (or 323.9°)

A + B - C = (32.98, 109.61)
Magnitude 114.5, direction 73.3°

C - A - B = -(A + B - C), so has the same magnitude (114.5) and opposite direction (73.3+180 = 253.3°).

Answer 2

Well for me thats true, i could never figure that out.