Lesson 3.1 Lines and Angles
Parallel Lines Two lines that are coplanar and do not intersect Symbol: II
Skew Lines Lines do not intersect and are not coplanar
Parallel planes Two planes that do not intersect Example 1 Give lines II to XY Give II planes Give lines skew to XY
Parallel Postulate If there is a line and a point not on the line then there is exactly one line through the point II to the given line.
Perpendicular Postulate If there is a line and a point not on the line, then there is exactly one line through the point perpendicular to the line.
Transversal A line that intersects two or more coplanar lines at different points. transversal
Angles formed by transversal Corresponding Angles: occupy corresponding positions. Alternate Exterior Angles: lie outside the 2 lines on opposite sides of the transversal.
Angles formed by transversal Alternate Interior Angles: Lie between the 2 lines on opposite sides of the transversal. Consecutive Interior Angles: (same side) lie between the 2 lines on the same side of the transversal.
Angle Relationships: Name a pair of angles Corresponding Ex. 1 & 5 Alternate Exterior Ex. 1 & 8 Alternate Interior Ex. 4 & 5 Consecutive Interior Ex. 3 & 5 1 2 3 4 5 6 7 8