What is a straight line connecting the two end points of an arc called?

The straight line connecting the two end points of an arc is called a chord. This term is specifically used in geometry and refers to a line segment whose endpoints lie on the circumference of a circle. A chord does not necessarily pass through the center of the circle; it simply connects two points on the arc.

In contrast, the other terms have distinct meanings: a sector is a region of a circle bounded by two radii and the arc that connects them; a segment refers to a portion of a circle cut off by a chord, which includes the arc and the area enclosed by the chord; while a tangent is a line that touches the circle at exactly one point and does not intersect the arc. Understanding these definitions helps clarify the concept of a chord within circular geometry.