\[
\alpha = \Delta \lambda \sin \phi
\]
Where:
$\alpha$ = angle of convergence
$\Delta \lambda$ = difference in longitude between the meridian
$\phi$ = latitude of the place
In cases where point A and point B are of not the same latitude $\phi$, the formula for the angle of convergence becomes:
\[ \alpha = \Delta \lambda \sin \phi_{mean} \] Where:
$\phi_{mean}$ = mean of latitude of point A and point B
Geodetic Azimuth: \[ \text {Geodetic Azimuth} = \text {Grid Azimuth} \pm \alpha \]
$\alpha$ = angle of convergence
$\Delta \lambda$ = difference in longitude between the meridian
$\phi$ = latitude of the place
In cases where point A and point B are of not the same latitude $\phi$, the formula for the angle of convergence becomes:
\[ \alpha = \Delta \lambda \sin \phi_{mean} \] Where:
$\phi_{mean}$ = mean of latitude of point A and point B
Geodetic Azimuth: \[ \text {Geodetic Azimuth} = \text {Grid Azimuth} \pm \alpha \]
