1.2+Points,+Lines,+Planes

=Chapter 1 Section 2=

Points, Lines, and Planes
David Raleigh __Point-__A point has no dimension. It is usually represented by a small dot.

__Line-__ A line extends in one dimension, and is represented by a straight line with arrows at the ends showing that it extends in both directions infinitely Lines, rays, and segments are very similar. A line has 2 arrows and goes on forever in both directions. A ray has one arrow and goes on forever in only one direction. Segments are just two points with no arrows, but a line connecting them.

Opposite rays are just like lines, but it is three points. Here is an example of opposite rays.

__Plane-__ A plane extends in two dimensions. It is usually represented by a shape that looks like a tabletop or wall. You must imagine that the plane extends without end, even though the drawing of a plane appears to have edges.

Points are showed as just dots and are labeled with a letter. Lines are labeled with two points and an arrow over them, signifying that it is a line. Planes can be labeled as some of the points on the plane or as the title of the plane.

Points that are collinear are points that are in a line. Two points are always collinear, and a line has an infinite number of collinear points.

Coplanar points are points that are all on one plane. Three points are always coplanar.

PRACTICE PROBLEMS


1. Name three points that are collinear.

2. Name four points that are coplanar.



3. Name the line that intersects both planes.

4. Are points F, D, B, and C coplanar?

5. Are points E and C collinear?

6. Are points E, B, and F coplanar?

Answers SOURCES McDougal Littell Geometry Textbook pages 10-17