A water main is to be laid from point A (N 1,200.00 m, E 800.00 m) to point B (N 950.00 m, E 1,100.00 m). The azimuth from north of line AB is most nearly:
- (A)39.8°
- (B)50.2°
- (C)129.8°
- (D)230.2°
Show worked solution
Answer: (C)
AB runs southeast ( m, m), so the bearing angle becomes azimuth .
Inverse from A to B.
Departure over latitude gives the angle off the meridian.
with places the line S 50.19° E; the azimuth folds back from 180°.
FE Reference Handbook — Civil Engineering, Surveying: Coordinate Inverse (Azimuth from Latitudes and Departures)
Why the other choices appear
- (A)Inverts the tangent ratio, computing arctan(250/300) = 39.8° and stopping without quadrant adjustment.
- (B)Reports the reference angle 50.2° (the bearing angle) without converting to an azimuth in the southeast quadrant.
- (D)Places the line in the southwest quadrant, computing 180° + 50.2° = 230.2° (sign error on the departure).