Final answer:
East to South represents a 90-degree turn in the clockwise direction on a compass, indicating an angular degree change from 90 degrees (East) to 180 degrees (South).
Step-by-step explanation:
The question 'Angular degree East to South =' refers to a directional measurement on the compass, where East is 90 degrees in the standard Cartesian coordinate system used for navigation and mapping. When moving from East around the compass to the South direction, you are moving in a clockwise direction, and the South is at 180 degrees in this system. Therefore, the angular degree from East to South is 90 degrees (from East to South).
This is similar to the examples provided, except the measurement is directly between two cardinal points rather than at a specified angle from one. For instance, 30.8 m, 54.2° north of east refers to moving northwards from the east direction at an angle of 54.2°, whereas East to South is a direct move without considering an additional angle.