Fore bearing and Back Bearing Confusion, Please help

ErAnushka

ErAnushka

@eranushka-4BgWe8 • Oct 27, 2024
Fore Bearing - Back Bearing = 180?

OR
Back Bearing - Fore Bearing = 180.

I fully understood the concept of meridian and bearing 😀

😲 But this thing is little confusing, as far as I know, Back Bearing - Fore Bearing should be 180, but I read somewhere that, Fore Bearing - Back Bearing = 180, but if you imagine, FB-BB would be negetive!

and let's say we have ABCD traverse,
Now, Let's start with line AB,
Back bearing of AB line - Fore bearing of AB line = 180,

But if we go further and take the line DA,
Fore Bearing of DA - Back Bearing of DA = 180,


Now I don't understand, why some people fixed FB-BB = 180?
or my imagination is wrong ? What's the correct method and principle?

Please explain me 😕
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  • Saiwal

    Saiwal

    @saiwal-NOzuWb • Sep 25, 2012

    there is no absolute relation between the forebearing and backbearing.
    Depending on the survey direction and location of north the following relation exists:
    Fore bearing = Back bearing ± 180°
    or
    Back Bearing = Fore Bearing ± 180°

    thus both your arguments are true.
    refer: #-Link-Snipped-#
    0
  • Jeffrey Arulraj

    Jeffrey Arulraj

    @jeffrey-xA7lUP • Sep 25, 2012

    We just use each one when the other is more than !80

    If FB=350 then BB=FB-180=170

    And if BB =350 then FB=BB-180=170
    0
  • ErAnushka

    ErAnushka

    @eranushka-4BgWe8 • Sep 25, 2012

    Saiwal
    there is no absolute relation between the forebearing and backbearing.
    Depending on the survey direction and location of north the following relation exists:
    Fore bearing = Back bearing ± 180°
    or
    Back Bearing = Fore Bearing ± 180°

    thus both your arguments are true.
    refer: #-Link-Snipped-#
    You saved my day! ☕ Thank you ^_^
    0
  • ErAnushka

    ErAnushka

    @eranushka-4BgWe8 • Sep 25, 2012

    jeffrey samuel
    We just use each one when the other is more than !80

    If FB=350 then BB=FB-180=170

    And if BB =350 then FB=BB-180=170
    I got it ^_^ Thank you 😀
    0
  • Jeffrey Arulraj

    Jeffrey Arulraj

    @jeffrey-xA7lUP • Sep 26, 2012

    Most welcome pal
    0
  • Rock Rohit

    Rock Rohit

    @rock-rohit-4WwEax • Oct 13, 2015

    If fb is 145 then what will be the BB
    0