Question

If the bearing of A from O is θ°T, then what is the bearing of O from A:
a. if 0° < θ° < 180°
b. if 180° < θ° < 360°?

I don't quite understand what the question is trying to ask, need some insight, thanks.

Answer 1

Draw a picture

say θ° is 30.
then from O to A is 180 + 30 = 210
for any θ° between 0 and 180, add 180
HOWEVER
once θ° is greater than 180, then when we add 180 it is bigger than 360
so to get it right you have to back up 180 and use θ° - 180

(or in fact you could still do it the same way and subtract 360 once you got 390 for example but that would be 180-360 = -180 anyway :)

Answer 2

or if A to O is east then O to A is west :} That might be where you got stuck.

Answer 3

riight, thanks. Appreciate it a lot Damon.