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CHAPTER 1.2. Point, Line, Plane. Activity. 1. Get into groups of 4, and define one of the following terms Point Line Plane 2. After you write down the definition, then take what you feel is the most important word in the definition and define that word.
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CHAPTER 1.2 Point, Line, Plane
Activity 1. Get into groups of 4, and define one of the following terms • Point • Line • Plane 2. After you write down the definition, then take what you feel is the most important word in the definition and define that word. 3. Perform this process at least 4 or 5 times.
Definition • Uses known words to describe a new word or phrase. • Therefore there has to be certain known words that are undefined to begin this process
Undefined Terms in Geometry • Even though we cannot define these terms, it is important to still be able to describe them • Our three undefined terms in geometry are • Point • Line • Plane
Points How to sketch: B * dots A How to label: C A * Use capital printed letters. * Never label two points with the same name (in the same sketch).
Lines How to sketch: NEVER n * must have arrows at both ends ? ? ? How to label: ? ? ? (Two methods) Possible Names: 1- small “script” letter 2- any two points on the line
Collinear Points Collinear points are points that lie on the same line. (The line does not have to be visible.) non-collinear collinear
Planes horizontal “edges” How to sketch: M * horizontal * vertical P vertical “edges” How to label: (Two methods) 1- capital “script” letter 2- any three points on the plane
Planes To label: any three points on the plane How many planes do you see?
Planes plane ABCD plane ABC plane BCD etc.
Planes plane EFGH plane GHE plane HEF etc.
Planes How many planes do you see? plane AEHD plane HDA plane AEH etc.
Planes How to label: any three (or more) points on the plane How many planes do you see? plane BFGC plane BFG plane FGC plane GCB plane CBF etc.
plane AFGD plane ACGE plane ACH Planes How to label: any three (or more) points on the plane Any three points determine a plane! plane AGF plane BDG etc.
Coplanar Coplanar objects (points or lines) are objects that lie on the same plane. (The plane does not have to be visible.) Definition: Are they coplanar? ABC ? yes ABCF ? NO HGFE ? yes EHCB ? yes AGF ? yes CBFH ? NO