Grid bearing Direction ( Geodetics )

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Hello all,

If someone knows about deciding the bearing direction, given latitude and longitude, that would be helpful. I don't quite get the logic.

here's an example.

Point 1:
Latitude: 41°15'18.000000"N
Longitude: 76°00'0.000000"W

Point 2:
Latitude:41°19'7.097720"N
Longitude: 75°54'55.972300"W

The calculated forward and reverse angles/Azimuth are :
Forward angle(from point 1 to 2):
45°00'00"

Reverse angle:
225°3'20.61"


The answer obtained for both forward and reverse azimuth is 45 degrees but for reverse I need to add 180 deg ie: 180+ 45 = 225 deg.

I don't understand the logic, whether to add to 180/360 or subtract from 180/360.


Note: I know the logic given eastings and northings but not the latitude and longitude.