Geometry Basics: Points, Lines, and Planes

• A point is a dot in space.
• A segment connects two points and has a beginning and an end.
• An array or ray has a beginning but no end and one arrow.
• A line has no beginning or end and extends infinitely in two directions.
• Points are collinear if they lie on the same line.
• Three or more collinear points determine exactly one plane.
• Coplanar points lie on the same plane.
• Non-coplanar points do not lie on the same plane.
• A plane can be determined by three non-collinear points, a line and a point, or two parallel lines.
• Two intersecting lines share the same plane.
• Coplanar lines exist on the same plane.
• Coplanar segments share the same plane as the segments they connect.
• Points determine the plane they lie on.
• Intersection of two planes is a line.
• A line and a point determine the plane they belong to.

Test your knowledge of the basic concepts in geometry including points, segments, rays, lines, and planes. Understand the relationships between points, lines, and planes, and how they intersect.