The equation for converting geodetic to grid azimuth is t = α - γ + δ, where t is the grid azimuth, α is the geodetic azimuth, γ is the convergence. The term δ is the

• A. Arc-To-Chord Correction
• B. Scale Factor Correction
• C. Convergence Correction
• D. Geoid Separation Correction

Answer: (A)

The key idea is that converting a geodetic azimuth to a grid azimuth must account for how directions change when moving from the curved ellipsoid to a flat map grid. The convergence term γ handles the rotation between true north and grid north caused by the projection. Beyond that rotation, there’s a distortion from representing a curved path (an arc on the ellipsoid) as a straight line on the grid plane. This arc-to-chord effect is what the δ term corrects for, ensuring the grid azimuth matches the direction on the map for the given geodetic direction. The other options relate to scale, vertical deflection, or geoid separation, which do not describe this angular correction.