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Geometry dots & lines


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Geometry dots & lines

  1. 1. Geometry Dots & Lines Made by Listening Daisy, based on notes from her Geometry Class (with permission from her instructor).
  2. 2. Table of Contents • Slide 3: What is a Point? • Slide 4: Mini Lesson: What Letters Not To Use When Naming Points • Slide 5: What Is A Line? • Slide 6: How To Name A Line • Slide 7: What Is A Line Segment? • Slide 8: What Is A Ray? • Slide 9: Name That Ray! • Slide 11: Mini Lesson: Additional Way to Name A Line • Slide 12: What Is Collinear? • Slide 13: What Is A Plane? • Slide 14: What Is Intersection? • Slide 16: Mini Lesson: Lines & Intersection • Slide 17: What Is Space?
  3. 3. What is a Point? • Points have no dimension they are “a place in space”. • When you name a point, use capital letters (usually the Roman Alphabet is used, but sometimes Greek letters are used). A
  4. 4. Mini Lesson: What Letters Not To Use When Naming Points When naming points, try not to use letters like T and S due to the fact they could be easily confused with something else. For example, S and 5 look very similar.
  5. 5. What Is A Line? BA AB Symbol for the line: • It has no end points • It has an infinite number of points • It is straight and not curved • Lines go off towards infinity in two directions
  6. 6. How To Name A Line • Now I’m sure you saw the symbol on the top right corner of the slide before this. is the abbreviation for a line, it is the name of the line. To make this symbol there must be at least two points on a line. Let’s use the line below as an example. • Since it has over two points, we can name it. You can only use two letters in the name however. • It is preferred that the letters of the name are read left to right as in the names AB, BC, & AC. It is also possible to use names like BA, CB & CA though. AB BA C
  7. 7. What Is A Line Segment? • Straight • Made up of points • To name it, you use the end points, not the points on the line. A B AB Symbol for the line:
  8. 8. What Is A Ray? • Ray: half a line, on one end it has a finite end point and on the other end it goes off infinitely • Straight • Needs two points to name: when naming, always start with the end point. It can’t be BA because BA is: A B AB Symbol for the line: BA
  9. 9. Name That Ray! Where are the rays? A B C
  10. 10. Name That Ray! A B C The rays that are located here are BA, BC & AC A B B C A C
  11. 11. Mini Lesson: Additional Way to Name A Line • An additional way to name a line is to use a lower case cursive letter.
  12. 12. What is Collinear? • When there are more then three points on the same line. • Ex 1: A, B & C are collinear • Ex 2: A, B & C are not collinear A B C A B C
  13. 13. What Is A Plane? • Flat • 2-dimensional • Named using its four points or a single cursive letter. or A B C D Note: The cursive letters must always be capitalized
  14. 14. What Is Intersection? • When lines cross, it’s in the form of a point • When planes cross it’s a line segment • When a line crosses a plane it’s a point.
  15. 15. What Is Intersection? • When three planes intersect, it’s a point.
  16. 16. Mini Lesson: Lines & Intersection • A line can only intersect at one point. • For example, due to the fact that the line is straight, it cannot curve to create another point inside the shape.
  17. 17. What Is Space? • A set of all possible points