Chapter Three:  
Parallel and Perpendicular Lines

Geometry   Notes

Chapter  3

Section  3.1
Section  3.2
Section  3.3
Section  3.4
Section  3.5
Section  3.6
Section  3.7

Geometry Contents

Take notes on the following topics.

Section 3-1  Properties of Parallel Lines

Vocabulary

Transversal (p. 115) A transversal is a line that intersects two coplanar lines in two points.

Alternate interior angles (p. 115) Alternate interior angles are nonadjacent interior angles that lie on opposite sides of the transversal.

Same-side interior angles (p. 115) Same side interior angles lie on the same side of the transversal t and between l and m.

Corresponding angles (p. 115) Corresponding angles lie on the same side of the transversal t and in corresponding positions relative to l and m.

Two Column Proof (p 117) A proof is a convincing argument that uses deductive reasoning. A proof can be written in many forms. In a two-column proof, the statements and reasons are aligned in columns. 

 

Postulate 3-1

If a transversal intersects two parallel lines, then corresponding angles are congruent.

Theorem 3-1

If a transversal intersects two parallel lines, then alternate interior angles are congruent.

Theorem 3-2

If a transversal intersects two parallel lines, then same-side interior angles are supplementary.