It's not too hard to understand zero, one, two, and three dimensions. What about four dimensions? What is the fourth dimension?
You live in a three dimensional world. Solid objects, such as yourself, are three dimensional. In order to better understand why your world is three dimensional, consider zero, one, and two dimensions:
A point has a dimension of zero. In math, a point is assumed to be a dot with no size (no length or width).
A line or line segment has a dimension of one. It has a length. A number line is an example of a line. To describe a point on a number line you only need to use one number. Remember that by definition, a line is straight.
You can think of the dimension of a space as the number of numbers it would take to describe the location of a point in the space. A single point on its own has dimension zero. A line, such as a number line, has dimension one. A plane, such as the rectangular coordinate system, has dimension two. A solid, such as a cube, has dimension three.
Determining Number of Dimensions
You graph a line on a rectangular coordinate system. How many dimensions does that line have?
Even though the rectangular coordinate system has two dimensions, the line itself has only one dimension.
Determining Number of Points
How many points make up a line?
A line is made up of an infinite number of points.
Is the edge of a desk best described as a point, a line, a plane, or solid?
The edge of a desk is best described as a line. It has one dimension.
Earlier, you were asked about the fourth dimension.
Four dimensions don't exist in our world, so it is very hard to imagine an object with dimension four. It helps to think about how two dimensions become three dimensions. A shape with dimension two moves up and down to create a solid with dimension three. Similarly, you can imagine a solid (such as a cube) with dimension three, moving within itself to create a tesseract, with dimension four.
Name three points with dimension zero from the figure above.
Name three line segments with dimension one from the figure above.
Name three planes with dimension two from the figure above.
1. In your own words, explain why a line has a dimension of one and a plane has a dimension of two.
2. Give a real-world example of something with a dimension of one.
3. Give a real-world example of something with a dimension of two.
4. Give a real-world example of something with a dimension of three.
Use the figure below for #5-#6.
Use the figure below for #7-#12.
7. Name three points from the figure above.
8. Name three line segments from the figure above.
9. Name three planes from the figure above.
13. A plane has a dimension of ____.
14. A line segment has a dimension of ____.
15. A cube has a dimension of ____.
To see the Review answers, open this PDF file and look for section 1.1.