Section 1-1, 1-3 Symbols and Labeling

Vocabulary Geometry –Study of the set of points Space –Set of all points Collinear –Points that lie on the same line Non-collinear –Points that do not lie on the same line

Vocabulary Continued Coplanar –Points that lie on the same plane Non-coplanar –Points that do not lie on the same plane Postulate –Statement accepted without proof

Point No size Simplest figure in geometry Named by –A capital letter Represented by a small dot Indicates a definite location

Line Series of points Extends in two opposite directions without end Name by –Two points on the line –Single lower case letter Has no thickness Is straight Can not be measured

Plane Flat surface Extends in all directions without end No thickness Named by –Single capital letter –Three non-collinear points on the plane Non-collinear –Points not on the same line

Segment Is part of a line Has two endpoints Can be measured Named by –Two endpoints

Ray Is part of line Has only one endpoint Extends in one direction without end Named by –The endpoint and any point on the ray Can not be measured

Opposite Rays Two rays that share a common endpoint and extend in opposite directions. They form a line

Parallel Lines Coplanar lines that do not intersect Segments and rays are parallel, if the lines that contain them are parallel A B CD

Skew Lines Lines that are in different planes They are neither parallel nor intersecting

Parallel Planes Planes that do not intersect Examples in this room –Plane of the floor and plane of ceiling –Horizontal planes never intersect –Vertical planes can intersect

Section 1-2 Angles Go to angles

1.1 postulates Postulate 1 –Two points determine one line Postulate 2 –Three non-collinear points determine exactly one plane

1-3 Postulates Postulate 3 –If two lines intersect, then their intersection is a point Postulate 4 –If two planes intersect, then their intersection is a line