1. Defined Terms

2. Objectives Yesterday, we talked about undefined terms. Today, we will focus on defined terms (which are based on the undefined terms from yesterday).

6. Space is the set of all points (objects in space have length, width, and height). A point is one point A line needs at least two points A plane needs at least three points Space needs at least four points What is space?

7. Collinear vs. Coplanar Collinear points are points all in one line. Coplanar points are points all in one plane.

8. Intersections The intersection of two figures is the set of points that are in both figures. You have intersections between lines, between planes, and between a line and a plane.

9. Line segments and betweenness A line segment is a part of a line. It has a fixed length and is named for its two endpoints. In the figure below segment AB consists of points A and B and all points that are between A and B. C is between A and B.

10. Rays A ray has one end point and extends in the other direction upto infinity. It is represented by naming the end point and any other point on the ray. Opposite rays are two rays with a common endpoint that point in opposite directions and form a straight line.

11. More about segments The length of a segment is always measured positively, like a distance. Congruent segments are segments that have equal lengths. The midpoint of a segment is the point that divides the segment into two congruent segments.

12. Even more about segments A bisector of a segment is a line, segment, ray or plane that intersects the segment at its midpoint.

13. Defined Terms - Summary Line segment Ray Intersection Bisector Midpoint Space coplanar