1. Activity 1 Points, Lines, and Planes Section 1.1

2. The most basic figures in geometry are undefined terms, which cannot be defined by using other figures. The undefined terms point, line, and plane are the building blocks of geometry. Who uses this???

3. Points A Point is named by a capital letter and represented by a dot. A point names a location and has no size J Called Point J All geometric figures are comprised of points. Slides 6-9 A tiny seed is a physical model of a point.

4. Lines A line has no thickness or width. It is an infinite set of points (extends forever). A line is named by 2 points on the line and by placing the line symbol above the letters. Slides 10-11 Example: Number Line

5. Slides 1-3 Line Segment A line segment consists of two points called endpoints of the segment and all the points between them. AD H A piece of spaghetti is a physical model of a line segment.

6. Congruent segments are segments that have the same measure or length. Slides 20-29 In the diagram, PQ = RS, so you can write PQ  RS. This is read as “segment PQ is congruent to segment RS.” Tick marks are used in a figure to show congruent segments. Congruent Segments

7. Rays Part of a line that starts at an endpoint and extends forever in one direction To name a ray, use its endpoint and any other point on the ray AD H A physical model of a ray are beams of light.

8. Collinear Points Points that lie on the same line. Non-collinear Points Points that do not lie on the same line. Slides 13-15 K L M N

9. Example: Name three collinear balls. Name three non- collinear balls.

10. Name this line. Slides 16-18

11. Plane A flat surface that extends indefinitely in all directions (consists of an infinite set of points) Named by 3 noncollinear points or a script capital letter. Slides 29-32 T

12. Name this plane. P

13. EXAMPLE Name the plane in 3 different ways. Give another name for Line AD. P

14. COPLANAR POINTS Points that lie in the same plane. NON-COPLANAR POINTS Points that do not lie in the same plane.

15. POSTULATE A postulate, or axiom, is a statement that is accepted as true without proof. Postulates about points, lines, and planes help describe geometric properties. Slides 19 - 28

16. Example 1: X N P R Y C A B 1.Name two collinear points. 2.Are A, B, and C coplanar? 3.Which plane(s) contain point X? 4. Are C, A, and B collinear? 5. Which plane(s) contain point C? 6.How many planes are in this figure? Name the planes

17. Example 2: Name 3 collinear points. How many planes are in this figure? Are points Y, A, W, and Z coplanar? Are points X, Y, and A coplanar?