is about the shape and size of things. Like algebra, geometry has its own special
vocabulary. These pictures show the four basic concepts on which the rest of
geometry is built.
your mouse cursor over each illustration to learn more.
part of a line that has two endpoints.
part of a line that has only one endpoint.
rays joined with a common endpoint.
plane is a flat surface that extends endlessly in all directions. Points that
lie on the same plane are called coplanar. Plane geometry deals with two-dimensional
point is a geometric object that has no dimensions, only a location.
line is a collection of points along a straight path, having no endpoints. Points
that lie on the same line are called collinear.
set of all points! Space geometry deals with three-dimensional figures.
are several other important terms.
Click on each to see what it means.