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  • Oct 17, 2010, 11:16 AM
    alliexo
    Trigonometry and Bearing
    A Ship sails 200km on a bearing of 243.7 degrees
    a. how far north has it travelled
    b. how far west has it travelled


    How am I supposed to calculate this? Please help
  • Oct 17, 2010, 02:34 PM
    kpg0001

    243.7 degrees from east(which is usually used as 0 degrees) would mean he would travel south and west not north. Anyway it's a pretty simple problem. First thing you should do is find the closest direction to this angle which would be straight south(270 degrees) so you are traveling 26.3 degrees west of south. Draw the (x,y) coordinate system and then draw a line that is coming from the origin(0,0) to somewhere about 26.3 degrees from south(this should be in the III quadrant). Now draw a line from the end of this directly to the y-axis(this should be parallel to the x-axis creating a right triangle). I know I kind of took the long way around but these are easier with a picture. So now you have a triangle and you know the hypotenuse(200km) and one of the angles(26.3 degrees). Now use trig functions to find the length in the x and y directions. The x length(same as west) will be 200sin(26.3) and the y length(same as south) will be 200cos(26.3).
  • Oct 18, 2010, 11:01 AM
    ebaines

    Usually bearings are measured from north, not east, in a clockwise direction. So a bearing of 243.7 degrees is actually heading 26.3 degrees sounth of west. Hence when asked "how far north has it traveled" you will get a negative answer, equal to 200Km x sin(-26.3).
  • Oct 18, 2010, 11:41 AM
    kpg0001

    The technique is correct and he should have been more specific, I'm not the captain of a ship.

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