Question

which model shows the radius?

Explanation:

To determine which model shows the radius, we recall the definition of a radius: a line segment from the center of a circle to any point on its circumference.

• The first model (left) shows a line passing through the center and touching two points on the circumference, which is a diameter (twice the radius), not a radius.
• The second model (middle) has a line segment with one endpoint at the center of the circle and the other on the circumference, matching the definition of a radius.
• The third model (right) shows the circumference (the curved edge of the circle) with arrows, not a radius.

Answer:

The middle model (the one with a line segment from the center to the circumference) shows the radius.