Proving Parallel Lines in Mathematics, Lecture notes of Mathematics

Various postulates and theorems related to proving that two lines are parallel in geometry. Topics include Postulates 10 and 11, Alternate Interior Angles Theorem, Same-Side Interior Angles Theorem, Perpendicular Lines, and various examples. Students of mathematics, particularly those studying geometry, will find this document useful for understanding the concepts of parallel lines and the different ways they can be proven.

Typology: Lecture notes

2021/2022

Uploaded on 09/27/2022

ekani
ekani 🇺🇸

4.7

(26)

265 documents

1 / 9

Toggle sidebar

This page cannot be seen from the preview

Don't miss anything!

bg1
October 21, 2016
How to Prove Lines are
Parallel
Mathematics is the gate and key to the sciences.
- Roger Bacon
Unit 3, Lesson 4
Postulate 11
If two lines are cut by a transversal and
corresponding angles are congruent,
then the lines are parallel.
pf3
pf4
pf5
pf8
pf9

Partial preview of the text

Download Proving Parallel Lines in Mathematics and more Lecture notes Mathematics in PDF only on Docsity!

How to Prove Lines are

Parallel

Mathematics is the gate and key to the sciences.

  • Roger Bacon Unit 3, Lesson 4

Postulate 11

If two lines are cut by a transversal and

corresponding angles are congruent,

then the lines are parallel.

Comparing postulate 10 to postulate 11, what do you notice?

Postulate 10

If two parallel lines are cut by a transversal,

then corresponding angles are congruent.

Postulate 11

If two lines are cut by a transversal and corresponding angles are congruent, then the lines are parallel. We can rewrite postulates 10 and 11 into a single statement....

Notice that this is the converse of Theorem 3-2. We can rewrite them as the Alternate Interior Angle Theorem

Two lines cut by a transversal are parallel if and only if
alternate interior angles are congruent.

Theorem 3-6 If two lines are cut by a transversal and same-side interior angles are supplementary, then the lines are parallel. Biconditional

You can add these to your theorem list book.

Can we also write the Alternate Exterior Angle Theorem and Same-Side Exterior Angle Theorem as biconditionals? Theorem 3- In a plane two lines perpendicular to the same line are parallel. Remember Skew lines

Theorem 3-

Through a point outside a line, there is exactly one line perpendicular to the given line. Example 1: State which segments (if any) are parallel? State the postulate or theorem.

Example 2: Example 3: Find the value of x and y to make