What to look for
In circle problems, you may need to identify one of five parts: radius, diameter, chord, arc, or tangent. The key is to use the definitions and the picture’s markings.
Step-by-step method
- Find the center. Many circle parts are described relative to the center.
- Check each segment or line:
- Radius: a segment from the center to a point on the circle.
- Diameter: a segment that goes through the center and has both endpoints on the circle.
- Chord: a segment with both endpoints on the circle, but not necessarily through the center.
- Arc: a curved part of the circle between two points on the circle.
- Tangent: a line that touches the circle at exactly one point.
- Use the labels carefully. If a point is marked as the center, segments connected to it are often radii or parts of a diameter.
- Match the term to the object shown. If the exercise asks for the name, write the correct term exactly.
Good check
Ask yourself: does it touch at one point only, pass through the center, or connect two points on the circle? That usually separates tangent, diameter/radius, and chord/arc.
Simplifying the final answer
If the answer is a word, make sure it is spelled correctly and matches the geometric feature shown.