1.1 Understanding Points, Lines, and Planes

Understanding Points, Lines, and Planes Undefined terms- words that cannot be defined by using other figures Point- has no size or dimension; names a location Line- straight path that has no thickness, extends forever in two directions Plane- flat surface that has no thickness, extends forever in two dimensions

Collinear- 3 or more points on the same line Coplanar- 3 or more points on the same plane

Segment (line segment) – part of a line, contains two points and all of the points between them Endpoint- points on the end of a segment or the starting point on a ray

Ray- part of a line, starts at an endpoint and extends forever in one direction Opposite ray- two rays that have a common endpoint and extend in opposite directions forming a line

Examples: a) Name 3 different segments b) Name the line 2 ways c) Name 4 different rays Add 3 points to the line.

Examples: a) Name 4 points that are coplanar b) Name 4 points that are not coplanar c) Name 3 points that are collinear Add a plane with two intersecting lines

Potulates (1.1.1) Two points determine a line (1.1.2) Three noncollinear points determine a plane (1.1.3) If two points are in a plane, then the line containing the points is also in the plane

(1.1.4) Two lines intersect at exactly one point (1.1.5) Two planes intersect at exactly one line

Examples: 3) Sketch two lines intersecting at exactly one point 4) Sketch two lines intersecting a plane at two points