Intro to Circles

The set of all points in a plane that are equidistant from a given point.

• Circle

• Semicircle

• Half Circle

• Point

The point in the middle. The point is used to name the circle.

• Center of a Circle

• Point

• Middle Dot

• Segment

The distance from the center of a circle to a point on the circle. Endpoints are the center and a point on the circle.

• Radius

• Circumference

• Diameter

• Segment Length

Distance across a circle, through the center of the circle.

• Diameter

• Radius

• Chord

• Segment

A segment whose endpoints are points on the circle.

• Chord

• Tangent

• Secant

• Angle

A segment that crosses the outside of the circle at two or more points and continues past the circle.

• Secant

• Tangent

• Chord

• Segment

A segment that touches a circle at exactly one point.

• Tangent

• Segment

• Secant

• Chord

The distance around the circle (perimeter)

• Circumference

• Area

• Circle

• Length

A segment of the circumference of a circle.

• Arc

• Tangent

• Major Arc

• Tangent

An arc whose endpoints of the circles diameter (half the circle).

• Semicircle

• Moon

• Arc

• Circumference