Lines - Geometry Made Easy
Welcome to Quatr.us Study Guides!

Line

Number Line
Number Line

July 2016 - A line is made of an infinite number of points that are right next to each other. A line goes on forever in both directions. In geometry, a line is always straight, so that if you know two points on a line, then you know where that line goes. A line is only one point thick (which is to say that it has no thickness, because a point has no thickness). When we mark off certain points on a line, we can use that line as a number line. When we draw a line with a pencil, we make it thick enough to see. But a line in geometry is not thick enough to see, because it is only one point thick. If you looked at a line from the end, it would look just like a point - so it would be invisible.

two perpendicular lines
Perpendicular lines

If you took a line and moved it through space, like sliding a flat ruler across a table, it would create a flat plane. You can create half a line by choosing one point on a line and naming the section of line that goes on from that point. You can also create line segments of any length by choosing two points on a line and naming the section between those two points. We use line segments for many things in geometry: one side of a triangle or a square is a line segment.

Two lines can be parallel to each other, or they can be perpendicular. If two lines are neither parallel nor perpendicular, then they are skew.

More about planes
More about Geometry

Bibliography and further reading about geometry:

More about Geometry
More Easy Math
Quatr.us home


For Presidents' Day, check out our articles about Washington in the Revolutionary War and Lincoln in the Civil War. Find out about the Constitution, the Bill of Rights and the other Amendments, and how Washington promised to include freedom of religion.
Please help other teachers and students find us: link to this page from your class page.
Karen Carr is Associate Professor Emerita, Department of History, Portland State University. She holds a doctorate in Classical Art and Archaeology from the University of Michigan. Follow her on Instagram or Twitter.
Cite this page
  • Author: K.E. Carr
  • Title:
  • Site Name: Quatr.us Study Guides
  • Publisher: Quatr.us
  • Date Published:
Proud of your class page, homework page, or resource page? Send it in and win a Quatr.us "Great Page!" award!
Sign up for more free articles and special offers in Quatr.us' weekly newsletter:
We will never share your e-mail address unless you allow us to do so. View our privacy policy. Easy unsubscribe links are provided in every email.
Comment on This Article

Cool stuff we've been enjoying: Looking for birthday gifts? Check out these new Chromebooks - all the computer you need for only $229.00!. Then study in peace with these Beats wireless headphones - for the exact same price! When you're done, show off your presentation or watch a movie with this excellent smartphone projector for only $39.99!


Does your class page honor diversity, celebrate feminism, and support people of color, LBGTQ people, and people with disabilities? Let us know, and we'll send you a Diversity Banner you can proudly display!
Looking for more?
ADVERTISEMENT
Quatr.us is loading comments...
(Comments will appear after moderation, if they are kind and helpful. Feel free to ask questions, and we'll try to answer them.)
Cite this page
  • Carr, K.E. . Quatr.us Study Guides, . Web. 22 February, 2017
ADVERTISEMENT