Points, Lines and Planes

Vocabulary: 

• Points,

• Lines,

• Planes,

• Collinear,

• Coplanar

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​Lesson 1: 

Undefined Terms

​Introduction

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​Lesson 1: 

Undefined Terms: Points, Lines, and Planes

​Introduction

​In mathematics, we tend to define vocabulary words using our prior knowledge.

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This means that we use previously understood words, terms, and concepts to formally define new vocabulary words.

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​Lesson 1: 

Undefined Terms: Points, Lines, and Planes

​Introduction

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There are, however, three words in geometry that are not formally defined.

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These words are...

points, lines, and planes..

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​Lesson 1: 

Undefined Terms: Points, Lines, and Planes

​Introduction

• ​Points, lines, and planes are the most basic terms in geometry. 

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• As they are the most basic geometric terms, we cannot depend on prior knowledge to define them.

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• These three words are referred to as the "three undefined terms of geometry."

​Lesson 1: 

Undefined Terms: Points, Lines, and Planes

​Introduction

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While these words are "undefined" in the formal sense, we can still "describe" them.

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This lesson will attempt to describe points, lines, and planes.

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Multiple Choice

Points, lines, and planes are called undefined

• True

• False

Multiple Choice

Points, lines, and planes are used to create definitions for other terms in Geometry.

• True

• False

Open Ended

Why does points, lines, and planes are called undefined terms?