Basic Geometry Concepts

Basic Geometry Concepts

POINTS

---We may think of a point as a "dot" on a piece of paper or the pinpoint on a board. In geometry we usually identify this point with a number or letter. A point has no length, width, or height - it just specifies an exact location. It is zero-dimensional.

The following is a diagram of points A, B, and M:



LINES

---A line is one-dimensional. That is, a line has length, but no width or height. In geometry, a line extends forever in both directions. A line is uniquely determined by two points.



The line passing through the points A and B
is denoted by line AB

LINE SEGMENTS

---A line segment connects two endpoints. A line segment with two endpoints A and B is denoted by line segment AB .



A line segment can also be drawn as part of a line.



MIDPOINT

----The midpoint of a segment divides the segment into two segments of equal length. The diagram below shows the midpoint M of the line segment AB . Since M is the midpoint, we know that the lengths AM = MB.



RAYS

---A ray starts from one endpoint and extends forever in one direction.



A ray starting from point A and passing through B
is denoted by ray AB

PLANES

---Planes are two-dimensional. A plane has length and width, but no height, and extends infinitely on all sides. Planes are thought of as flat surfaces, like a tabletop. A plane is made up of an infinite amount of lines. Two-dimensional figures are called plane figures.



A plane



Here is a video: