Chord

A chord is a line segment connecting two points on a circle. Equal-length chords span equal angles in the centre.

Circle

All points in a plane that have a fixed distance (radius) from a fixed point (centre).

Circular arc

Part of a circle’s boundary, characterized by its radius and a certain angle.

Circular sector

Part of a disk bounded by two radii and a circular arc.

Circular segment

A region of a circle which is “cut off” from the rest of the circle by a secant or a chord.

Circumcircle

The circumcircle of a polygon is the circle that passes through all of its vertices.

Circumference

The perimeter of a circle or ellipse.

Cone

A three-dimensional object with a flat base (mostly a circle) that tapers linearly to its apex point. The volume is 1/3 times base area times height.

Congruent

Two objects are congruent of they have the same shape and size.

Convex

In a convex shape, any line segment that joins two points on or in the shape will lie entirely on or inside of the shape. Convex polygons have interior angles that are each less than 180 degrees.