Final answer:
The distance of a survey is measured by setting a known baseline and then using angles and trigonometry to calculate the length to a remote object, like a tree across a river, using the concept of parallax.
Step-by-step explanation:
The distance of a survey refers to measuring the length between two points, often using the principles of geometry and trigonometry. For instance, when surveyors need to measure the distance to an object that cannot be reached directly, such as a tree across a river, they use a method that incorporates a baseline and observes the phenomenon of parallax.
A baseline is a known distance between two points from which measurements are taken. In surveying, angles from each end of the baseline to the object are measured. By applying trigonometry, specifically the tangent function, the distance to the object can be calculated.
For example, if a surveyor establishes a 100-meter baseline and measures an angle of 35° to a tree across a river, they can determine the width of the river by calculating the length of the perpendicular from the baseline to the tree. This example illustrates basic surveying techniques, showcasing how surveyors measure distances that cannot be physically traversed.