How is a deflection angle defined?

A deflection angle is defined as the angle between a line and its extension. This means it is measured from the endpoint of a line to the direction in which that line would extend indefinitely. When surveying or in civil engineering applications, this concept is crucial for determining changes in direction along a survey line or a road alignment.

Unlike a right angle, which is a specific measurement of 90 degrees and does not serve the purpose of defining a deflection between two lines, or an angle from the horizontal which pertains to elevation or slope but does not convey the relationship between extensions, the definition of a deflection angle directly relates to understanding how two lines connect, intersect, or change course. This is especially important in geometric design and layout, where knowing how far off from a straight path a line deviates is necessary for accurate construction and planning. The difference between two adjacent lines is also not relevant as it does not specifically capture the essence of how an angle is formed between a line and its continuation. Thus, the definition capturing the relationship between the original and extended line is the most accurate description of a deflection angle.