===Radius from true anomaly=== where a is the orbit`s semi-major axis (segment cz). ...
The angular distance of a point in an orbit past the point of periapsis, measured in degrees.
(from the article `anomaly`) ...are distinguished to describe the position in the orbit of a planet, a satellite, or a star (in a binary system) around the centre of mass. The ... ...terms, such as perigee and apogee for the Earth, are often used to indicate the primary body. If is the instantaneous location of a planet in its ... [...
The angular distance of a point in an orbit past the point of periapsis, measured in degrees. 
[n] - the angular distance of a point in an orbit past the point of periapsis measured in degrees
noun the angular distance of a point in an orbit past the point of periapsis measured in degrees