1.  1.2 Points, Lines, and Planes Unit 1, Day 1

2. Do Now  Match the word with its informal definition. (Copy in your notes.) 1.Extends infinitely in one dimension. 2.Has no dimension. 3.Extends infinitely in two dimensions A.Point B.Plane C.Line

3. More Vocabulary  Points are said to be collinear if they lie __________________________  Points are said to be coplanar if they lie _________________________

4. Let’s think…  You can draw a line through any _____ points. So in order to name noncollinear points, you need at least ________.  You can draw a plane through any ______ points. So in order to name noncoplanar points, you need at least ________.

5. Ex. 1: Naming Collinear and Coplanar Points a. Name three points that are collinear. b. Name four points that are coplanar. c. Name three points that are noncolinear. G D E F H

6. More Vocabulary  The line segment AB ( _____) consists of the endpoints ___ and ____ and all of the points on line AB that are _______________.  The ray AB (______) consists of the initial point ___ and all of the points on line AB that are on the same side as point ____.  Ray AB and ray BA are not the same!

7. More Vocabulary  If C is between A and B, then ray CA and ray CB are considered ___________________.  Note: When we say “between” in this class, it implies that the three points are on the same line.

8. Ex. 2: Drawing lines, segments and rays  Draw three noncollinear points, J, K, and L. Then draw JK, KL and LJ.

9. Ex. 3: Drawing Opposite Rays  Draw two lines, MN and PQ, that intersect at a point, X. Name two pairs of opposite rays.

10. Intersection  Two or more geometric figures are said to intersect if _______________________________.  The intersection is the set of points the figures have in common (usually another figure!).  Line with plane:  Plane with another plane:

11. Closure  Suppose rays CA and AT are opposite rays. What does this tell you about the points C, A, and T?