Geometry 3.1 Big Idea: Identify pairs of lines and angles Big Idea: Identify pairs of lines and angles

Vocabulary Parallel Lines: Two lines that do not intersect and are coplanar.

Skew Lines: Two lines that do not intersect and are not coplanar.

Parallel Planes: Two planes that do not intersect. Ex: plane RSTU || plane WXYZ

Note: a small triangle (like an arrow, pointed in one direction of a line) is used to indicate that lines are parallel (our book uses red color to denote this) – the arrow is on each line, not at the end

Postulates Postulate 13:Parallel Postulate If there is a line and a point not on the line, then there is exactly one line through the point ║ to the given line.  P m

Postulate 14:Perpendicular Lines If there is a line and a point not on the line, then there is exactly one line through the point ┴ to the given line.  P m

More Vocabulary Transversal: A line that intersects 2 or more coplanar lines at different points.

Corresponding Angles: on same side of transversal with same relationship (on top or on bottom) to other 2 lines (2 & 6), others?

Alternate Interior Angles : Angles that lie between the 2 lines on opposite sides of the transversal (3 & 5), others?

Alternate Exterior Angles: Angles that lie outside the 2 lines on opposite sides of the transversal. (2 & 8), others? (2 & 8), others?

Consecutive Interior Angles: Angles that lie between the 2 lines on the same side of the transversal.(4 & 5 ),others?

Example: Identify all pairs of angles of the given type. Corresponding Alternate Interior Alternate Exterior Consecutive interior Vertical