Which term describes a line segment from the center of a circle to the boundary?

• A. Diameter
• B. Chord
• C. Arc
• D. Radius

Answer: (D)

The line from the center of a circle to any point on its boundary is called the radius. A radius is a straight segment with one endpoint at the center and the other endpoint on the circle, and every radius of the same circle has the same length. This is why it’s the specific term for that description.

Think about how other circle terms differ: a diameter is a segment that goes all the way across the circle, passing through the center and connecting two boundary points, so it’s twice as long as a radius. A chord is any segment whose endpoints lie on the circle, but it doesn’t have to pass through the center. An arc is just a portion of the circle’s boundary, not a straight line.

So the correct term for a line segment from the center to the boundary is the radius.