#1Starting at point A, a ship sails 18.5 km on a bearing of 189°, then turns and sails 47.8 km on a bearing of 317°. Find the distance of the ship from point A.

I'd asked for help on yahoo answers, and the people there told me this

x = 18.5cos 189° + 47.8cos 317° = 16.686

y = 18.5sin 189° + 47.8sin 317° = -35.494

distance = (16.686)² + (-35.494)² = 39.220 km

it's the correct answer in the book, but I dont understand where the equations came from..

#2What bearing and airspeed are required for a plane to fly due north in 2.5 hours if the wind is blowing from a direction of 328° at 11 mph?

I know that the plane is currently at 160 mph now, but then I dont know how the picture would even look like so I'm not sure where to begin...

Please help, I hate bearing problems