Intro to Parallel Lines Notes 4.5 Intro to Parallel Lines
Plane a surface such that if any two points on the surface are connected by a line, all points of the line are also on the plane. Coplanar – lie on the same plane. Noncoplanar – Do not lie on the same plane.
PARALLEL LINES l Definition: lines that do not intersect. Notation: l || m AB || CD A B C D l m
PERPENDICULAR LINES m n Def: Lines that intersect to form a right angle. Notation: m n Key Fact: 4 right angles are formed. m n
Transversal A line that intersects 2 lines at 2 different points . Forms 8 different angles. 1 2 3 4 6 5 7 8
Vertical Angles ∠1 & ∠ 3 ∠2 & ∠ 4 ∠5 & ∠ 7 ∠6 & ∠ 8
Linear Pairs – 2 angles that make a line ∠1 & ∠ 2 ∠1 & ∠ 4 ∠2 & ∠ 3 ∠3 & ∠ 4 ∠5 & ∠ 6 ∠6 & ∠ 7 ∠7 & ∠ 8 ∠5 & ∠ 8
Corresponding Angles ∠1 & ∠ 5 ∠2 & ∠ 6 ∠3 & ∠ 7 ∠4 & ∠ 8 (Same place on different line) ∠1 & ∠ 5 ∠2 & ∠ 6 ∠3 & ∠ 7 ∠4 & ∠ 8
Alternate Interior Angles ∠3 & ∠ 5 ∠4 & ∠ 6
Alternate Exterior Angles ∠1 & ∠ 7 ∠2 & ∠ 8
Same Side Interior Angles Consecutive Interior Angles ∠3 & ∠ 6 ∠4 & ∠ 5