Parts of a Circle

Parts of a Circle (Extended)

Circle: A locus (collection) of points that are equidistant to a point (centre).

Circumference: The perimeter of a circle.

Radius: A line that connects the centre of the circle to its circumference.

Chord: A line connecting two points on the circumference of a circle.

Diameter: A chord that passes through the centre of the circle.

Sagitta (Outside Syllabus): A line perpendicular to a chord that connects the midpoint of the chord to the circumference.

A circle can be divided into Sectors that are enclosed by 2 radii and a piece of the circumference (Arc).

Sometimes for clarity, the smaller sector will be referred to as the Minor Sector while the larger one is referred to as the Major Sector. The same goes for Minor Arcs and Major Arcs.

A circle can be divided into Segments that are enclosed by a chord and a piece of the circumference (Arc).

Similarly, the smaller segment is usually referred to as the Minor Segment and the larger one is referred to as the Major Segment.

Lines and Circles

Secant: A line that intersects a circle at 2 distinct points.

Tangent: A line that intersects a circle at exactly 1 point. The tangent will be perpendicular to the radius of the circle at that intersection point.

Passant (Obscure word): A coplanar line that does not intersect with a circle