# Geometry Lesson 1 1 Points Lines and Planes

• Slides: 15

Geometry Lesson 1 – 1 Points, Lines, and Planes Objective: Identify and model points, lines, and planes. Identify intersecting lines and planes.

Undefined terms: objects that are only explained using examples and descriptions. Point l Line l Plane l

Point: l. A point is a location. l Has neither shape nor size Named: l Capital letter Example l Point A

Line: Made up of points l Has no thickness or width l Exactly one line through and two points. l Named: Any 2 points on the line (2 capital letters) l Lowercase script letter l Example l l line m or

Plane: Plane A flat surface made up of points that extends infinitely in all directions. l Exactly one plane through any 3 points not on the same line. l Named Capital Script letter l 3 points on the plane not on a line (3 capital letters) l Example K l l Plane BCD (any order)

Definitions Collinear: l Points that lie on the same line Noncollinear: l Points that do not lie on the same line. Coplanar l Points that lie in the same plane Noncoplanar l Points that do not line in the same plane

Use the figure to name each of the following: A line containing point W Any one of the following work: A plane containing point X Any one of the following work: (3 letters that are noncollinear) P, plane XZY, plane VZW, plane WZX, plane VZX, Plane WZY

Example Name the geometric term modeled by the objects in the picture. l Push pin l Maroon boarder l The card itself Point G Sample: plane FGJ l Stripes on a sweater l Corner of a box point lines

Intersection of two or more geometric figures is the set of points they have in common. Where do two lines intersect? At a point. Where do two planes intersect? At a line

Draw the following intersects plane T at point S. Sample answer Must have the dashed line to show that the line goes through the plane and is not on or in the plane.

Draw the following Line p lies in plane N and contains point L. Sample answer.

Definitions are defined terms that are explained using undefined terms and/or other defined terms. Space: defined as a boundless, threedimensional set of all points. Space can contain lines and planes.

How many planes appear in this figure. 6 planes: 5 around the pyramid and one on bottom of the pyramid… don’t name the bottom plane twice. Name 3 points that are collinear. Points J, K, and D Make sure you have commas otherwise it names a plane. Name the intersection of plane HDG with plane X. At what point do LM and EF intersect? Explain. Don’t appear to intersect since L is the only point on line LM in the plane.

Are points E, D, F, and G coplanar? No, not all on the same plane. At what point or in what line do planes JDH, JDE, and EDF intersect? Point D is the only thing in common.

Homework Pg. 8 1 – 12 all, 14 – 46 EOE, 52, 66 – 82 EOE