3-4 Parallel and Perpendicular Lines
Objective
To relate parallel and perpendicular lines
In the Solve It, you likely made your conjecture about Oak Street and Court Road based on their relationships to Schoolhouse Road. In this lesson you will use similar reasoning to prove that lines are parallel or perpendicular.
Essential Understanding You can use the relationships of two lines to a third line to decide whether the two lines are parallel or perpendicular to each other.
Take Note: Theorem 3-7
Theorem
If two lines are parallel to the same line, then they are parallel to each other.
If …
Then …
You will prove Theorem 3-7 in Exercise 7.
Table of Contents
- 6-1 The Polygon Angle-Sum Theorems
- 6-2 Properties of Parallelograms
- 6-3 Proving That a Quadrilateral Is a Parallelogram
- 6-4 Properties of Rhombuses, Rectangles, and Squares
- 6-5 Conditions for Rhombuses, Rectangles, and Squares
- 6-6 Trapezoids and Kites
- 6-7 Polygons in the Coordinate Plane
- 6-8 and 6-9 Coordinate Geometry and Coordinate Proofs