1. Chapter 3.1 Notes Parallel Lines – 2 lines that do not intersect and are coplanar Parallel Planes – 2 planes that do not intersect Skew Lines – 2 lines that do not intersect and are not coplanar

2. 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. If then Perpendicular Postulate – If there is a line and a point not on the line then there is exactly one line through the point and perpendicular to the given line Ifthen

3. Identifying Angles Formed by Transversals Transversal – is a line that intersects 2 or more coplanar lines at different points. Transversal Corresponding Angles 1 2 3 4 Alternate Interior Angles 5 6 7 8 Alternate Exterior Angles Consecutive Interior Angles (Same-Side Int. Angles)

4. Chapter 3.2 Notes Flow Proof – uses arrows to show the flow of the logical argument. Thm – if 2 lines intersect to form a linear pair of congruent angles, then they are perpendicular. If then Thm – if 2 sides of 2 adjacent acute angles are perpendicular, then the angles are complementary. If then 1 2 m ∠ 1 + m ∠ 2 = 90°

5. Thm – If 2 lines are perpendicular, then they intersect to form four right angles If then

6. Chapter 3.3 Notes Corresponding ∠ Post. Alt. Int. ∠ Thm Alt. Ext. ∠ Thm Cons. Int. ∠ Thm

7. Perpendicular Thrasversal Thm – If a transversal is perpendicular to one of 2 parallel lines, then it is perpendicular to the other. Ifthen

8. Chapter 3.4 Notes Four ways to prove two lines are parallel. 1) Show Corr. ∠’s are ≌ 2) Show Alt. Int. ∠’s are ≌ 3) Show Alt. Ext. ∠’s are ≌ 4) Show Same Side are Supp. (Cons. Int. ∠’s are supp.)

9. Chapter 3.5 Notes Thm – Is 2 lines are parallel to the same line then they are parallel to each other. * If p II q and q II r, then p II r. p q r Thm – In a plane, if 2 lines are perpendicular to the same line, then they are parallel to each other. * If m ⊥ p and n ⊥ p, then m II n.

10. Chapter 3.6 Notes Slope = Risem = y – y 1 y = mx + b Run x – x 1 Two lines are parallel if they have the same slope.

11. Chapter 3.7 Notes 2 Lines are Perpendicular to each other if their slopes are negative reciprocals of each other. Ex. m = 2/3 and m 1 = -3/2 then they would be perpendicular lines