Lines at right angles to each other are said to be __________ to each other.

Lines that are at right angles to each other are described as perpendicular. This geometric term indicates that the angle formed between the two lines is exactly 90 degrees, which is the defining characteristic of perpendicularity. In many applications, including engineering, design, and construction, understanding the relationship between perpendicular lines is crucial, as it affects the structural integrity and functionality of various elements.

The other terms relate to different geometric relationships. Tangential refers to a line that touches a curve at a single point without crossing it, while equal denotes a relationship where two entities have the same size or value without any specific orientation implication. Coincide means that two lines or figures occupy the same space or position, which does not necessarily imply right angles. Understanding these distinctions is essential in the context of geometry and engineering.