Lesson 3: 6-3: Tests for Parallelograms

1. How can we use the conditions of parallelograms to prove if a quadrilateral is a parallelogram?
2. Which methods would you use first in determining whether a quadrilateral that is graphed on a coordinate plane is a parallelogram?

G.CO.11
Prove theorems about parallelograms.
G.CO.12
Make formal geometric constructions with a variety of tools and methods (compass and straightedge, string, reflective devices, paper folding, dynamic geometric software, etc.)
G.GPE.4
Use coordinates to prove simple geometric theorems algebraically.

The properties of parallelograms can be used to determine whether a quadrilateral is a parallelogram. If a quadrilateral is graphed on the coordinate plane, the Distance Formula and the Slope Formula can be used to determine whether it is a parallelogram.

Lexi and Rosalinda cut strips of bulletin board paper at an angle to form a hallway display (shown on pg. 443). Their friends asked them how they cut the strips so that their sides were parallel without using a protractor.

Students approaching grade level can be given practice problems in small groups to work with other students or directly with the teacher.
Students beyond grade level can make deeper connections working with a partner. One student can draw a parallelogram in a coordinate plane. The partner then proves the drawing is a parallelogram.

Formative Assessment

Textbook in class

Access online textbook and resources through class link.