1-2: Points, Lines, & Planes

1. 1-2: Points, Lines, & Planes p. 12-18

2. Point 1. Has no dimension (no length, width, thickness) 2. Usually represented by a dot 3. Named using one capital letter • B

3. Example of a point • Point H is not on plane R or P • Where is point C? • Sometimes I write point as pt, so point C would be pt C

4. Line • Extends forever in one dimension (length) • Has an arrowhead on each end representing the fact that it goes on forever • Consists of an infinite amount of points • Always straight • Named with a lowercase script letter or by 2 points on the line Can be called: Line l Line AB or AB Line BA or BA l A B

5. Example of a line • Name the line GB as many ways possible • Line GB, BG, FB, BF, FC, CF, GC, CG, FG, GF, BC, CB or • GB, BG, FB, BF, FC, CF, GC, CG, FG, GF, BC, CB

6. Plane • Extends forever in 2 dimensions (length & width) • A flat surface consisting of infinitely many points • Usually represented by a 4-sided figure • Named with a capital script letter or 3 non-collinear points on the surface of the plane Can be named: 1)Plane W or 2)Plane ABC, plane BCA, plane CBA, etc. A W C B

7. More Definitions • Coplanar points – points that lie on the same plane

8. Line Segment (or segment) • A section of a line that has 2 endpoints • Named by its endpoints. AB or BA • Order doesn’t matter with segments A B

9. Ray • Piece of a line with only one endpoint (initial point) and continues forever in the other direction • Named by the endpoint and a second point named on the ray. (name MUST begin with the endpoint!) AB A B

10. Opposite Rays • 2 rays that share a common initial point and face opposite directions. • QP and QS are opposite rays. • What do they form? a line P Q S

11. Example: 6 volunteers please! Sketch and label a diagram to represent the following : • MN • PQ • RP • Lines AB and CD intersect at E. • Line n contains Y and W, but not Z • C is on AB but not on AB

12. When 2 planes intersect, their intersection is a … Line • Name the intersection of Plane P and Plane R • Line AB or BH

13. When a line intersects a plane, their intersection is a … Point Name the intersection of line n with the plane K

15. Homework:p. 15 (3, 7-17, 19-36, 43-51)