**Geometry Chapter 3.1 Lines and Angles**:

**I) Vocabulary**:

**A) Parallel Lines**(ll): two lines that are coplanar and do not intersect.

**B) Skew lines**: two lines that doe not intersect and are not coplanar.

**C) Parallel Planes**: Planes that do not intersect.

**II) Postulates**:

A) If there is a line and a point not on the line, then there is exactly one line through the point parallel to the given line.

B) If there is a line and a point not on the line, then there is exactly one line through the point perpendicular to the given line.

**III) Identifying Angels formed by transversals:**

**A) Transversal**: is a line that intersects two or more coplanar lines at different points.

**B) Corresponding angles**: if you have two lines that are intersected by a transversal, the the two angles that occupy the same position - (eg. to the left of the transversal and on top of the two lines)

**C) Alternate interior angles**: if you have two lines that are intersected by a transversal, then the two angles that lie between the two lines and on opposite sides of the transversal.

**D) Alternate exterior angles**: if you have two lines that are intersected by a transversal, then the two angles that lie outside the two lines on opposite sides of the transversal.

**E) Consecutive Interior Angles**: two angles if they lie between the two lines on the same side of the transversal. Also known as same side interior angles.