Short Answer 
A secant line intersects a circle at two points, which in this case is demonstrated by line segment AB that crosses the circle without passing through its center (point D). To confirm it’s a secant, it must meet the criteria of intersecting the circle at two distinct points and not passing through the center, all of which are satisfied by line segment AB.
Step 1: Identify the Secant Line
To determine whether a line is a secant, first look for a line segment that intersects the circle at two points. In this case, line segment AB meets this criterion as it crosses through the circle without passing through its center. Understanding this basic definition of a secant is key in distinguishing it from other lines.
Step 2: Analyze the Circle’s Features
Next, identify the center of the circle, which is commonly marked as a specific point, in this scenario referred to as point D. Knowing where the circle’s center is located helps to visualize the circle correctly. A secant will not pass through this center but will still touch the circle at two defined points.
Step 3: Confirm the secant line
Finally, reinforce your understanding that the line segment AB, in this situation, clearly qualifies as a secant. To summarize, you can confirm this by checking the following:
- Does line segment AB intersect the circle in two distinct points?
- Does it not pass through the center point D?
- Is it represented as line segment AB?
Since all these conditions hold true, we can conclude confidently that the secant line is indeed line segment AB.