Basic Circle Properties: A circle is defined by all points equidistant from its centre. This constant distance from the centre to any point on the circle is called the radius.

Key Circle Measurements: The diameter is twice the radius and stretches across the circle through the centre. A chord is any line segment connecting two points on the circle, with the diameter being the longest chord.

Parts of a Circle: A segment is the area between a chord and its arc, while a sector is the “pie-slice” area formed by two radii and the arc between them.

Tangents: A tangent is a line that touches the circle at a single point and is always perpendicular to the radius at that point of contact.