What are the undefined term in geometry?

Answer 1

The 3 terms are point, line, and plane. Do not be intimidated by the the phrase "undefined." You may already know a pretty good definition for these terms, especially the first two.

• A point is like a star in the night sky. It is a little spec in a large endless sky. However, unlike starts, geometric points have no size. Think of them as being so small that they take up zero amount of space.
• A line is like the edge of a ruler, that never ends. Take a ruler and draw a line - now imagine if that line kept going straight forever. The line you have is thick enough for you to see, but you need to imagine that your line is so thin that you can't see it - it has no thickness at all. That is a geometric line.
• A plane is a flat piece of land (like a football field) that extends forever. Imagine that you can pick that football field up, and put it anywhere in the air that you like. You can even turn it side ways, or diagonally. A plane is just a flat edge (like a piece of paper) that has no thickness (just like the line) and extends forever.

  -tonton^_^

Answer 2

They are

1. a point;
2. a line;
3. a plane.