1 2 Points Lines and Planes Geometry Mrs

1. 2 Points, Lines and Planes Geometry Mrs. Lutz Mrs. Sant Mrs. Berrett

Objective n Understand such as and use geometry terminology – Point – Line – Plane – Collinear points – Midpoint – Line Segment - Ray - Opposite rays - Infinite - Parallel - Perpendicular

Example what your note page should look like now 1. 2 Points, Lines, & Planes Objectives: Name______________ Date__________Period_____ Class_______________

Points Point A • A point has no dimension. It is usually represented by a small dot. • You can think of a point as a location. • Points are named by a capital letter. A

Lines • A line extends in two opposite directions. l • Name a line with two points or A a single lowercase letter. • A line has one-dimension. B Line l or AB

Collinear Points n Collinear points are points that lie on the same line. n Points A, C, and B are collinear points. A C B

Ex. 1: Naming Collinear Points Name three points that are collinear H G D Solution: D, E and F lie on the same line, so they are collinear. E F

Ex. 2: Naming Collinear Points Name three points that are not collinear. H G D E Solution: There are many correct answers. For instance, points H, E, and G do not lie on the same line. F

Planes • • A plane extends in two dimensions. A A plane is usually represented by a shape that looks like a tabletop or wall. M C B Plane M or plane ABC • Imagine that the plane extends without end, even though the drawing of a plane appears to have edges.

Coplanar n Coplanar means together on the same plane. A Points A, B and C are coplanar. M C B

Skewed Lines n Skewed lines are not in the same plane and do not intersect.

Inifinite l. n Consider the line n How many points are there between A and B? l B There an infinite number of points between two points. Line A l

Line Segments A B Segment AB n The line segment or segment AB (symbolized by AB) is named by its endpoints. The line segment includes points A and B and all points in between.

Rays A B Ray AB n The ray AB (symbolized by AB) is named by its endpoint and a second point B. n The ray contains point A and all points to the right on AB.

l More. . . n B Note that AB is the same as BA and AB is the same as BA. A Line n l or AB AB and BA are not the same. They have different starting points and extend in different directions. A B Ray AB A B Ray BA

Opposite Rays n l Opposite rays are two collinear rays that share an endpoint. B C A Line n If C is between A and B, then CA and CB are opposite rays. l or AB

Parallel Lines n Lines Line l that do not intersect. ll Line m Line l Line m

Perpendicular Lines that intersect at a 90 o angle. n Lines l т Line m m Line l