1. 1.2 Points, Lines, and Planes

2. What is a definition? Known words used to describe a new word Known words used to describe a new word Undefined terms – are terms not formally defined. There are three undefined terms in geometry: 1. Point2. Line3. Plane

3. Point 1. A location in space. 2. Has no dimension (no length, no width, no depth). 3. Usually represented by a dot. 4. Named using one capital letter. 5. All geometric figures consist of points POINTS ARE TO GEOMETRIC FIGURES AS ___________ IS TO HUMANS? POINTS ARE TO GEOMETRIC FIGURES AS ___________ IS TO HUMANS?

4. Point For example: ●B●B●B●B What would be a real world example of a point?

5. Line 1. A series of points that extends in opposite directions without end. 2. One-dimensional (length). 3. Has an arrowhead on each end representing the fact that it goes on forever. 4. Always straight. 5. Named with a lowercase script letter or by 2 points on the line

6. Line A B l Can be called: Line l Line AB or AB Line BA or BA For example: Real World example?

7. Plane 1. A flat surface that extends forever in two dimensions (length & width). 2. Contains infinitely many points and lines. 3. Usually represented by a four-sided figure. 4. Named with a capital script letter or 3 points on the surface of the plane

8. Plane A B C W Can be named: Plane W Plane ABC, plane BCA, plane CBA, etc. **Planes can be named by more than 3 points, but they must be named in either a clockwise or counter-clockwise manner For example: Real World example?

9. Horizontal Planes – Ceiling and Floor Horizontal Planes – Two sides horizontal and no sides vertical

10. Vertical Planes – Walls Vertical Planes – two sides are vertical

11. More Definitions Collinear points – Collinear points – points that can lie on the same line. **Think of the suffix “CO” as sharing.**

12. More Definitions Noncollinear points – Noncollinear points – D

13. More Definitions Coplanar points – What does it mean? Coplanar points – What does it mean? points that can lie on the same plane.

14. More Definitions If the points do not lie in the same plane they are? If the points do not lie in the same plane they are? Noncoplanar points – Noncoplanar points – D A

15. More Definitions Equidistant – equally distant Equidistant – equally distant

16. Classify each statements as true or false REMOTE TIME !

17. Question 1 PF ends at P

18. Question 2 Point S is on an infinite number of lines

19. Question 3 A plane has no thickness

20. More Definitions Intersect – Intersect – – Two or more figures intersect if they have one or more points in common. – Think “meet” or “Cut” Intersection – Intersection – – All points or sets of points the figures have in common. – Depending on what is intersecting, the intersection will be different

21. When a line and a point intersect, their intersection is a point. B l Like taking a road trip and driving through a certain town or city on the map.

22. When 2 lines intersect, their intersection is a point. Like the intersection of Foothill and Ramsdale

23. When 2 planes intersect, their intersection is a line. The planes are cutting through one another

24. When a line and plane intersect, their intersection is a point. Like sticking a pencil through a piece of paper

25. Questions???

26. Question 4 Collinear points are coplanar

27. Question 5 Planes have edges

28. Question 6 Two planes intersect in a line segment

29. Question 7 Two intersecting lines meet in exactly one point

30. Question 8 Points have no size

31. Question 9 Line XY can be denoted as XY or YX.

32. Partner Share: True or False All points on a line are coplanar

33. True or False A line has one endpoint

34. True or False A point is named by a capital letter.

35. True or False Two lines intersect in two points.