Basic geometry: language and labels
Notes from Khan Academy video Basic geometry: language and labels | Introduction to Euclidean geometry | Geometry | Khan Academy
- Word geometry is made up of 2 components: "geo" and "metry":
- "Geo" - earth
- "metry" - measurement
- Therefore, geometery is about how shapes and space (things we see) related to each other.
- A plane is a flat surface that has 2 dimensions: width and height and goes on infinity in either direction.
A point refers to a dot on that plane and is the most basic geometric idea.
A line that connects 2 points, is refered to as a line segment
- A line segment is described using its endpoints: the points that it is connected by.
In math notation, a line is drawn over the endpoints to denote that it's a line segment.
The endpoints of a line segment can be inversed:
A line segment is one-dimension - you can move back and forth along it.
A line that starts from one point that continues on infinitely in one direction is called a Ray
A line that continues infinitely in either direction is formally called a line.
A line is described by the endpoints it intersects, typically in alphabetical order though the order does not matter.