Relationships Between Lines Parallel Lines – two lines that are coplanar and do not intersect Skew Lines – two lines that are NOT coplanar and do not intersect Perpendicular Lines – two lines that intersect to form a right angle Parallel Planes – two planes that do not intersect

Parallel and Perpendicular 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 parallel to the given line. Postulate 14: 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 given point. l P * l

Transversals A transversal is a line that intersects two or more coplanar lines at different points.

Angles Formed By Transversals Corresponding Angles – two angles are corresponding if they occupy corresponding positions as a result of the intersection of the lines. (1 & 5) Alternate Exterior Angles – two angles are alternate exterior if they lie outside the two lines on opposite sides of the transversal (1 & 7) Alternate Interior Angles – Two angles that lie between the two lines on opposite sides of the transversal (4 & 6) Consecutive Interior Angles – two angles that lie between the two lines on the same side of the transversal (4 & 5) Who can name another pair for each of the angle types above?