Question

A girl walks 800meters on a bearing of 129degrees calculate how far east and south is from her starting point

Answer 1

I made a sketch on an x-y grid, and it shows her ending up in the 4th quadrant
at (800cos39°, 800sin39°) or (.... , .....)

Answer 2

All angles are measured CW from +y-axis.
D = 800m[129o] = 800*sin129+800*cos129 = 622-503i.
D = 622 m. East and 503 m South.