Hi Charlie P.,
Let vector V = A + B + C + D
A = 21*cos(269) i + 21*sin(269) j
B = 12*cos(155) i + 12*sin(155) j
C = 23*cos(33) i + 23*sin(33) j
D = 21*cos(161) i + 21*sin(161) j
V = -11.808661 i + 3.438247 j
The magnitude of the vector is the distance from the starting point.
|V| = √(11.8086612 + 3.4382472) = 12.3 km
I hope this helps, Joe.