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1.2 Points, Lines and Planes Geometry Mrs. Lutz Mrs. Sant Mrs. Berrett Objective Understand and use geometry terminology such as – 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 Collinear points are points that lie on the same line. 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 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. 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 Coplanar means together on the same plane. A Points A, B and C are coplanar. M C B Skewed Lines Skewed lines are not in the same plane and do not intersect. Inifinite l. Consider the line How many points are there between A and B? l B There are an infinite number of points between two points. Line A l Line Segments A B Segment AB 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 The ray AB (symbolized by AB) is named by its endpoint and a second point B. The ray contains point A and all points to the right on AB. l More . . . B Note that AB is the same as BA and AB is the same as BA. A Line 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 l Opposite rays are two collinear rays that share an endpoint. B C A Line If C is between A and B, then CA and CB are opposite rays. l or AB Parallel Lines Lines that do not intersect. Line l ll Line m Line l Line m Perpendicular Lines Lines that intersect at a 90o angle. Line l т Line Line m m Line l