Clarification/Follow-up by aab072588 on 07/11/05 5:38 pm:
thanks for your response again. i have another question thoug - how do you know that the angle between the two sides is 317 - 189?

Clarification/Follow-up by Jim.McGinness on 07/12/05 9:09 am:
I'm glad you're still asking questions. Clarify a few things for me, so I can try to help your further.

When you read these problems, do you understand what the term "bearing" means? It's a compass direction where north is 0 degrees, south is 180 degrees, etc.

When the ship is sailing on a bearing of 189 degrees, it is traveling just a little bit westerly of due south. When it turns to travel on a bearing of 317, it is going nearly north-west. The two legs of the journey make an angle whose measure is the difference in the two bearings, hence 317-189 or 128 degrees.

But I was wrong to say that this is the angle of the triangle. It's the outside angle through which the ship turns. The inner angle -- which is what you'd use for the triangle, is 128-180, or 52 degrees.

It's much clearer if you draw yourself a diagram -- something which answerway doesn't have good facilities for....