Given point 1 (φ1, λ1), azimuth1-2, distance12, determine point 2 (φ2, λ2) and azimuth21. This geodesic problem is commonly called:

Given point 1 (φ1, λ1), azimuth1-2, distance12, determine point 2 (φ2, λ2) and azimuth21. This geodesic problem is commonly called:

• A. Geodetic direct
• B. Geodetic inverse
• C. Geodetic cross-section
• D. Geodetic projection

Answer: (A)

Forward geodetic problem on an ellipsoid: given a starting point, the initial azimuth, and the distance along the ellipsoid, determine the destination point and the final azimuth. This setup matches the direct geodetic problem, where you move from a known location along a specified initial direction for a given distance and compute where you end up and what the ending bearing is. The inverse problem would start from two known points and yield the distance and both azimuths between them, which is not the case here. In practice this is solved with indirect methods like Vincenty’s direct formulae on the ellipsoid.

Forward geodetic problem on an ellipsoid: given a starting point, the initial azimuth, and the distance along the ellipsoid, determine the destination point and the final azimuth. This setup matches the direct geodetic problem, where you move from a known location along a specified initial direction for a given distance and compute where you end up and what the ending bearing is. The inverse problem would start from two known points and yield the distance and both azimuths between them, which is not the case here. In practice this is solved with indirect methods like Vincenty’s direct formulae on the ellipsoid.