Which of the following statements is/are true about the meridional radius of curvature?

The meridional radius of curvature, denoted as M, is a parameter in geodesy that describes how the curvature of the Earth changes with latitude along a meridian. Understanding how this concept works helps clarify why all the provided statements are indeed true.

The first statement highlights that the meridional radius of curvature and the prime vertical radius are minimum at the equator. This is accurate because, at the equator, the Earth's curvature is less pronounced—making the radius of curvature in the meridional direction smaller. This aspect reflects the Earth's oblate spheroid shape, which affects how curvature is measured.

The second statement concerns the specific relationship at the pole, indicating that M equals ( \frac{a^2}{b} ) at that location. At the poles, the curvature is influenced by the semi-major axis (a) and semi-minor axis (b) of the ellipsoid. This statement correctly describes the mathematical relationship inherent in terrestrial measurements.

The third statement discusses the relationship between N (the radius of curvature in the prime vertical direction) and M. It asserts that N is always greater than or equal to M, with equality holding true only at the poles. This is consistent with the geometric properties of an ob