Sec. 1 – 4 Segments, Rays, Parallel Lines and Planes Objectives: 1) Identify segments and rays. 2) Recognize parallel lines.
What would you call two lines which do not intersect? Parallel A solid arrow placed on two lines of a diagram indicate the lines are parallel. The symbol || is used to indicate parallel lines. AB || CD
A slash through the parallel symbol || indicates the lines are not parallel. AB || CD
Skew Lines – Two lines are skew if they are not in the same plane and do not intersect. AB does not intersect CD . Since the lines are not in the same plane, they are skew lines.
1-3 Use the figure below. Name all segments that are parallel to AE . Name all segments that are skew to AE . Parallel segments lie in the same plane, and the lines that contain them do not intersect. The three segments in the figure above that are parallel to AE are BF , CG , and DH . Skew lines are lines that do not lie in the same plane. The four lines in the figure that do not lie in the same plane as AE are BC , CD , FG , and GH .
Parallel Lines ~ coplanar lines that do not intersect Skew Lines ~ noncoplanar They are not parallel & they do not intersect Same direction & Same plane Different direction & Different plane Lines that do not intersect may or may not be coplanar.