Lesson 4: 6-4: Special Parallelograms - Rectangles

1. What tools might help you solve problems involving rectangles?
2. What properties prove that a parallelogram is a rectangle?

Rectangle

G.CO.11
Prove theorems about parallelograms.
G.GPE.4
Use coordinates to prove simple geometric theorems algebraically.
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.)

A rectangle is a parallelogram with four right angles. If a quadrilateral is graphed on a coordinate plane, the Slope Formula can be used to determine whether consecutive sides are perpendicular. The Distance Formula can be used to calculate the measures of the diagonals. The diagonals of a rectangle are congruent.

Leonardo is in charge of set design for a school play. He needs to use paint to create the appearance of a doorway on a lightweight solid wall. The doorway is to be a rectangle 36 inches wide and 80 inches tall. How can Leonardo be sure that he paints a rectangle?

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 by working together to make conjectures about the diagonals in a rhombus or square.

Formative Assessment

Textbook in class

Access online textbook and resources through class link.