1.2 Points, Lines, & Planes – def. HMWK: pp. 14 – 15, # 44 – 60 all Game Plan: Today I will be able to (TIWBAT) understand and apply basic definitions undefined terms. Warm-up: Imagine you are teaching someone how to use a computer. What vocabulary words would you want this person to learn? Why is it important for them to understand the meaning of these words?

1.2 Points, Lines, & Planes – def. Definitions v. Undefined Terms Definitions: uses known words to describe a new word. Undefined terms: not formally defined, but accepted agreement of definition.

1.2 Points, Lines, & Planes – def. Undefined Terms Name 1.Point –Thought of as a “dot” to show location –No dimension Notation / Sketch 1.Point –Capital letter A B 2. Line –Straight, infinitely long in both directions –Made up of an infinite number of points –One dimensional 2. Line –Always two capital letters

1.2 Points, Lines, & Planes – def. Undefined cont. 3.Plane –Though of as a flat surface –Extends infinitely in all directions. –Two dimensional 3. Plane –Either Plane “M” or Plane “ABC” –Drawn like a table top M

1.2 Points, Lines, & Planes – def. Some more undefined terms … Remember a point lies on a line or a plane Collinear points: –points that line on the same line Coplanar points: –points that line in the same plane.

1.2 Points, Lines, & Planes – def. Basic Definitions Consider the line Line Segment (segment): –Consists of endpoints, A and B, –All points on between A and B Ray: –The initial point, A, and all points onthat lie on same side of A as point B. A B

1.2 Points, Lines, & Planes – def. Basic Definitions cont Consider the following statement …. A B

1.2 Points, Lines, & Planes – def. Almost last definition Consider the following line Opposite rays: AC B

1.2 Points, Lines, & Planes – def. Last definition!! Intersect: having one point in common. Intersection: set of points in common.

1.2 Points, Lines, & Planes – def. Sketch the following … 1.Draw 3 collinear points A, B, and C. Draw point D which is not collinear with A, B, and C. Draw 2.Sketch a line and a plane that do not intersect. 3.Two planes that do not intersect and a line that intersects each plane in one point.

1.2 Points, Lines, & Planes – def. Wrap Up What is the difference between undefined and defined terms?