Geometry Chapter 1 Section 2 Points Lines Planes

Geometry Chapter 1 Section 2 Points, Lines, & Planes

Point • Undefined term in geometry • Represents the simplest geometric concept • It is a location in space (indicates position). • All geometric figures consist of points. • Represented as a dot

Points - graphically. ● A ● ● B ● C D

Line • Undefined term in geometry • Consists of an infinite number of points • Extends in opposite directions • Goes on FOREVER

Identifying & Representing Lines • The minimum number of points needed to identify a line is two. ● A B ● l • A way we represent the above line is… l

Points & lines • If all of the points lie on the same line, then the points are collinear. • If all of the points don’t lie on the same line, then the points are non-collinear.

Plane • Undefined term in geometry • Sort of like a flat geometric “wall” • “ 2 dimensional” • Consisting of an infinite number of points • Infinite in size

Identifying & Representing Planes • The minimum number of points needed to identify a plane is 3. B A P C • A way to represent a plane is… ØP (pick a capital letter) or ØABC (3 non-collinear points…use capital letters)

Points & Planes • If all of the points lie in the same plane, • then the points are coplanar. • If all of the points don’t lie on the same plane, • then the points are non-coplanar.

Dashes in diagrams indicates parts hidden from view in figures in space. A Q B R S C N P

Intersection • The intersection of two figures is the set of points that are in both figures.

True or False? N X b M A Y P 1. 2. 3. 4. 5. 6. 7. 8. P is in M b is in M YX contains P M contains XY A is on b A & P are in M N contains P A & P are collinear

Homework: Section 1. 2 Written Exercises (p. 7 -9) #1 -18 & 27 -31