Question

which defines a circle?
two rays with a common endpoint
a piece of a line with two endpoints
a piece of a line with one endpoint
all coplanar points equidistant from a given point

Explanation:

• Analyze Option 1: Two rays with a common endpoint define an angle, not a circle.
• Analyze Option 2: A piece of a line with two endpoints is a line segment, not a circle.
• Analyze Option 3: A piece of a line with one endpoint is a ray, not a circle.
• Analyze Option 4: By the definition of a circle, it is the set of all coplanar points that are at a fixed distance (radius) from a given point (center). So this option correctly defines a circle.

Answer:

D. all coplanar points equidistant from a given point