v
1.1 Identify Points, Lines, and Planes Undefined Terms: Points, lines and planes are undefined terms in Geometry. These have no formal definition, they are just basic ideas. Point: has ____________ dimension, represented by a dot. ŸA or Point A Line: has _____________dimension, represented by a line with two arrowheads to show it extends without end. *Through any two points there is exactly one line. A line is named using two points that lie on it. Example 1: Give 5 names for the following line: Plane: has ______________dimensions, represented by a flat surface (table top, wall, etc.). There are two ways to name the plane below. By the letter M without the point symbol that appears on the corner of the plane, or by the points located inside the plane. *Through any three points not on the same line there is exactly one plane. Example 2: Give 2 names for this plane. Collinear: points that lie on the same ________________________________. Coplanar: points that lie on the same ________________________________. 1 Example 3: 
a.)
Give two other names for PQ and for plane R b.)
Name three points that are collinear. c.)
Name four points that are coplanar. 
d.)
Give another name for ST . e.)
Name a point that is not coplanar with V, S, & T. v Defined Terms Segment: a piece of a line. Segments have two endpoints. Written as: Ray: Rays have one endpoint and extend forever in one direction. Written as: *Unlike lines and segments, we can not switch the order of the points for a ray. (Name ALWAYS starts with the endpoint). Opposite rays: Two rays that share the same endpoint and create a straight line. Example 4: a.) Give another name for PR . b.) Name all rays with endpoint Q. 2 c.) Which of these rays are opposite rays? Intersection: one point or a set of points that a figure has in common. 1.) When two lines intersect, they intersect at a _______________________________. 2.) When two planes intersect, they intersect at a _____________________________. 3.) A line and a plane intersect at a _______________________________________. 3