- a line segment
- a one-dimensional object of finite length with two end points
- a ray
- a one-dimensional object with one end point
- a line
- a one-dimensional object with no end points
- to intersect
- an angle
- two rays with a common end point
- a vertex
- the point where the rays of an angle intersect
- equidistant
- as far away, same distance
- a circle
- a set of points that are equidistant from a single point
- a center/centre
- the point in the exact middle of a circle
- a radius
- a line segment that connects the centre of a circle to a point on its outer rim
- a chord
- a line segment that connects a point on the outer rim of a circle to another
- a diameter
- a chord that passes through the centre of the circle
- semi-
- internal
- external
- a tangent
- a line external to a circle that intersects the circle once