Geometry 1-1 Understanding Points, Lines, and Planes

Building Blocks of Geometry 3 noncollinear points

Lines and Planes  collinear -Points that lie on the same line.  noncollinear- Points that do not lie on the same line. (at least 3)  coplanar -Points that lie on the same plane.  noncoplanar- Points that do not lie on the same plane.  collinear: K, L, M  noncollinear: N, L, M M K L N

Segments and Rays

What’s the Difference?  Line segment: –Finite length –Two endpoints  Ray: –Infinite length in one direction –One endpoint  Line: –Infinite length in both directions –No endpoints

Key Theorems  If two lines intersect, they intersect at a point.  If two planes intersect, they intersect at a line.  If a line and a plane intersect, they intersect at a point.

Know the difference A line in a plane A line intersecting a plane