Final answer:
Baseline measurements serve as a reference for angular displacement using the horizon, equator, and the concept of parallax. The horizon and azimuth are used in surveying, while the equator is important in astronomy for measuring declination.
Step-by-step explanation:
Baseline measurements are fundamental in establishing a point of reference to express direction and measure angular displacement. One common baseline used is the horizon, where the angle is measured counterclockwise from north to other directions such as east (90°), south (180°), and west (270°). This is commonly used in surveying with instruments like theodolites.
A second baseline often used is the equator, which astronomers use as a reference to measure the declination of celestial bodies above or below this celestial line. Lastly, the concept of parallax demonstrates the importance of a baseline, which is the apparent shift in position of an object when observed from two different points. Surveyors use this method by establishing two observation points (the baseline) to measure the distance to a remote object.
The azimuth is another method to express angular direction, which is measured in degrees. This measurement from the azimuth zero point, typically north, moves clockwise around the compass. It is important to establish the azimuth zero based on the orientation of the map or the conventions of the discipline (surveying, astronomy, etc.).