Assessment and Learning in Knowledge Spaces (ALEKS) Practice Exam

What defines a circle?

1. A shape with three sides

2. Set of points equidistant from a center point

3. A polygon with equal angles

4. A closed figure with straight sides

The correct answer is: Set of points equidistant from a center point

A circle is defined as a set of points that are all equidistant from a central point, commonly referred to as the center. This definition captures the essence of what a circle is: every point on the circumference of the circle is the same distance from the center, which is the distinguishing characteristic of this shape. This uniform distance is known as the radius. Other possible definitions mentioned in the choices focus on different shapes and forms. For instance, a shape with three sides refers to a triangle, which has a completely different structure. Similarly, a polygon with equal angles describes a regular polygon, such as a square or equilateral triangle, rather than a circle. Lastly, a closed figure with straight sides could refer to many different shapes, like squares, rectangles, and triangles, but does not encompass circles as they have a curved boundary. Therefore, the choice defining a circle as a set of points equidistant from a center point most accurately describes the geometry of a circle.