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-   -   Bearings and trigonometry? (https://www.askmehelpdesk.com/showthread.php?t=416000)

  • Nov 14, 2009, 04:53 PM
    trach171
    Bearings and trigonometry?
    Three towns A, B and C are connected by straight roads. B is due west of A, C is due south of B and the bearing of C from A is 220 degrees. If the distance from A to B is 300 km:

    a) find the distance from A to C

    b) find the bearing from A to C
  • Nov 14, 2009, 05:15 PM
    jmjoseph
    Based on what you have given, the distance between A and C is 466.7 km, and the bearing from A to C is 220 deg. The bearing from C to A is the reciprocal, 40 deg.

    (Edited)
  • Nov 14, 2009, 09:31 PM
    Unknown008
    1 Attachment(s)

    Sorry, but the distance is not good.

    The easiest way to do it is by having a sketch in front of you.

    Attachment 26502

    You can find angle BAC by having 270 - 220 = 50 degrees
    Using cos, you know that



    Solving for AC will give you 466.7 m.

    Then, the bearing is indeed 40 degrees
  • Nov 16, 2009, 01:27 AM
    Unknown008

    Quote:

    Originally Posted by jmjoseph
    I used the diagonal of a 300km x 300km square, and I was obviously wrong. OOPS. I mis-read something. Thanks. Unk!

    It's OK, it might have happened to anybody including myself :)

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