Section 1 1 Identify Points Lines and Planes

Section 1. 1 – Identify Points, Lines, and Planes �Divide the top half of your paper into three vertical columns. The titles for the columns should be Points, Lines, and Planes �Try to write a definition of each of these terms in your columns �This is a difficult task as these are actually known as “undefined terms” in Geometry!

Section 1. 1 – Identify Points, Lines, and Planes � What do we use to represent a point? • A point is represented by a dot � How many dimensions does a point exist in? • It has no dimensions (this will make more sense soon) � What is the best way to communicate to someone which point we are talking about in the diagram? • We label each point with a Capital letter

Section 1. 1 – Identify Points, Lines, and Planes � What do we use to represent a point? • A point is represented by a dot � How many dimensions does a point exist in? • It has no dimensions (this will make more sense soon) � What is the best way to communicate to someone which point we are talking about in the diagram? • We label each point with a Capital letter • Example: Point B

Section 1. 1 – Identify Points, Lines, and Planes � How do we represent a line? • An infinite number of dots (points) put together in a straight row with arrows on the ends � Why the arrows? • A line extends forever in both directions � How many dimensions does a line exist in? • One dimension (left-right is one dimension, up-down is another, and forwardbackward is another)

Section 1. 1 – Identify Points, Lines, and Planes �

Section 1. 1 – Identify Points, Lines, and Planes � How do we represent a plane? • Something that looks like a floor or wall (but really extends forever) � How many dimensions? • A plane exists in two dimensions � What is it called if it goes forever in three dimensions? • Space • Sometimes to emphasize the three dimensions we call it “ 3 -space”

Section 1. 1 – Identify Points, Lines, and Planes � How do we name a plane? • Option one: a single letter (that is not referencing a point) �Example: plane R • Option two: three points that are NOT in a straight line, but are on the plane �Example: plane EFG

Section 1. 1 – Identify Points, Lines, and Planes �More definitions: �Collinear • Points that are all on a line together • Noncollinear = NOT on the same line �Coplanar • Points, lines, etc. that are all on a plane together • Noncoplane = NOT on the same plane

Section 1. 1 – Identify Points, Lines, and Planes �

Section 1. 1 – Identify Points, Lines, and Planes �

Section 1. 1 – Identify Points, Lines, and Planes �

Section 1. 1 – Identify Points, Lines, and Planes � What do you think it would take for two rays to be opposite rays? • They have to have the same endpoint and go in completely opposite directions • Thus opposite rays are collinear

Section 1. 1 – Identify Points, Lines, and Planes �

Section 1. 1 – Identify Points, Lines, and Planes � What is formed when two different lines intersect? • A point, like point P

Section 1. 1 – Identify Points, Lines, and Planes �

Section 1. 1 – Identify Points, Lines, and Planes � Examples: a. Sketch a plane and a line that is in the plane b. Sketch a plane and a line that does not intersect the plane c. Sketch a plane and line that intersects the plane at one point

Closure �On a half sheet of paper (to turn in when you are finished) write down: � 3 vocabulary words from today’s lesson �A drawing of 2 planes intersecting � 1 question that you have �Homework: page 5 #3 -13, 17 -23, 44