C. N. Colón Geometry St. Barnabas H. S. Bronx, NY The Building Blocks: Undefined Terms Ch 1.1
A definition is a statement that gives the meaning of a term.
They really don’t exist. But if they don’t exist, then geometry doesn’t exist. But geometry does exists so they must exist. ~But they don’t… so what can we do????
A set is a collection of objects such that it is possible to determine whether a given object belongs to a collection or not.
A set implies that objects belong together. Examples include: The students in this class as found on a list Crayons found in a box Musical notes found in a scale
A point is a specific place. It has no size at all. No length, no width, no depth. It is represented by a dot. It is named with capital letters. ● A ● B ● C
A. A nail on the wall B. A floor tile on the floor C. The buttons on the projector.
A line is a straight arrangement of points. It has infinite length. It goes on forever in each direction. It is named by two points. Pick two points on the line and place a small line (with arrows) on top. It can also be named by one lower case letter.... A B C l ABACBCCA line l
The points can form a straight line or they can form a curved line In this geometry class the word line will mean a straight line
A. The place where the wall and the ceiling meet. B. The floor. C. The power cord on the projector.
A plane is a flat surface that goes forever in all directions. It has infinite length and infinite width, but no depth. It is named using three points. A plane can also be named by a script capital letter. It can be represented by any flat surface. Examples of a plane: your desktop, a piece of paper, the whiteboard.
When two points lie in the same plane they are coplanar. Points M, N, and O are coplanar.
True or False? The ceiling is a real-life example of a plane.