Answer:
Arc: a curved line that is part of the circumference of a circle. The arc of a circle is measured in degrees or radians - for example: 90° or 2π - a quarter of the circle, 180° or π - a half of the circle. The arc is smaller than 360°(or 2 π \displaystyle 2\pi 2π) because that is the whole circle.
Chord: a line segment within a circle that touches 2 points on the circle.
Arc: a curved line that is part of the circumference of a circle.
Radius: the distance from the center of a circle to any point on it.
Sector: is like a slice of pie (a circle wedge).
