The angle in the plane of projection between a straight line and the central meridian of a rectangular coordinate system is Called _______ azimuth.

• A. geodetic
• B. grid
• C. magnetic
• D. astronomic

Answer: (B)

In map projections that use a rectangular coordinate system, directions are measured relative to the grid north, which runs along the central meridian. The angle between a line and that central meridian, measured in the projection plane, is the grid azimuth. This reference is tied to the map’s coordinate system rather than the true surface of the Earth, which is why grid azimuth is distinct from other azimuth types that reference geodetic, astronomical, or magnetic north. The other names—geodetic, astronomic, and magnetic azimuths—depend on different north references (the ellipsoid’s north, true astronomical north, and magnetic north, respectively), so they don’t describe the angle shown in the projection plane relative to the central meridian.