**1.1: Understanding Points, Lines, and Planes**

**Definitions:**

Point - Names a location and has no size it is represented by a dot.

**Line**- A __straight__ path that has no thickness and extends forever.

**Plane** - A flat **surface** that has no thickness and extends forever.

**Segment** - The part of a line consisting of __two points__ and __all points between__ them.

**Endpoint** - A point at __one end of a segment__ or starting point of a ray.

**Ray** - A part of a line that __starts at an endpoint__ and extends __forever in one direction__.

**Opposite** **Rays** - Two rays that have a __common endpoint__ and form a line.

Postulates:

1. Through any two points there is exactly one line.

2. Through any three noncollinear points there is exactly one plane containing them.

3. If two points lie in a plane, then the line containing those points lies in the plane.

Point

Postulates:

**Examples:**