2. GEOMETRY’S UNDEFINED TERMS POINTLINEPLANE

3. POINT A point is a location, or a place.

4. POINT A point is not a physical object – you can not touch it, feel it, or even see it.

5. POINT A point has no size.

6. POINT A point can be represented by a dot. The size that you make the dot is not important because a point has no size. Make it just large enough to see.

7. POINT A point is named by using an “upper-case” “block” letter. EXAMPLE: P This figure would be called “point P”.

8. POINT EXAMPLE 2: X This figure would be called “point X”.

9. LINE A line is a set of points that extends infinitely in 2 opposite directions. What does “infinitely” mean ? NEVER-ENDING (Goes on forever.)

10. LINE EXAMPLE : Why does it have arrows on both ends ? TO SHOW THAT IT EXTENDS INFINITELY IN BOTH (OPPOSITE) DIRECTIONS

11. NAMING A LINE There are 2 ways: 1. Use the names of (any) two points on the line. Example: P X What name(s) can we give to this line? Line PX or line XP

12. NAMING A LINE There are 2 ways: 2. Use a “lower-case” “cursive” letter (located near one of the arrows). Example: What name can we give to this line? Line m m

13. NAMING A LINE There are 2 ways: 2. Use a “lower-case” “cursive” letter (located near one of the arrows). 1. Use the names of (any) two points on the line. EXAMPLE : line PX (OR USE A “SYMBOL” FOR LINE AND WRITE IT ABOVE THE LETTERS.) PX EXAMPLE: line m or m

14. How many names does this line have? R G K h There are 7 different names that you could use to name this line. They are: RG, GR, RK, KR, GK, KG, h HOW MANY DID YOU GET ???

15. Let’s try again. How many names does this line have? F N X t There are 7 different names that you could use to name this line. They are: FN, NF, FX, XF, NX, XN, t DID YOU DO BETTER THIS TIME ?

16. ONE MORE TIME. How many names does this line have? T Y N There are 12 different names that you could use to name this line. They are: TC, CT, TY, YT, TN, NT, CY, YC, CN, NC, YN, NY C GOT IT ?????

17. PLANE A plane is a “flat surface” – a set of points that extends infinitely in 2 dimensions. What does “dimension” mean ? Length, Width, Height. A plane is infinitely long and infinitely wide, but it has no height (or depth).

18. PLANE A plane can be drawn (represented) by a four sided figure known as a parallelogram.

19. PLANE A plane can be named by a single “upper-case” “block” letter (written near a corner of the plane). Q What is the name of this plane? Plane Q or □Q

20. What is the name of this plane? R N T F ANSWER: PLANE F WHY CAN’T IT BE CALLED PLANE R or T or N ? R, T, and N are names of points. There is no point near “F”.