CONGRUENCE IN QUADRILATERALS:

LESSON 18Before we begin Lesson 18, let’s check our homework.

OBJECTIVES:1. Know and be able to use

both necessary and sufficient conditions for quadrilaterals to be (special) parallelograms.

Quadrilaterals come in a variety of specialized shapes.

They are trapezoids, kites, parallelograms, rhombi,

rectangles and squares, as well as quadrilaterals with no

special additional characteristics.

PICTURES OF QUADRILATERALS:

Pull out the worksheet called “Properties/Theorems About Parallelograms.” Let’s discuss the properties of parallelograms and draw the illustrations.Now, pull out the flowchart and we will discuss all the properties of the different types of quadrilaterals.

1) If AG = -4k + 24 and DG = 9k + 102, find BD.

2) If AB = 2x + 3 and BC = 5x, find AD, AEB and ∠ABC.

B

A C

D

E

3) Parallelogram DEFG is below.

DH = y + 4, HF = 3x – 1, GH = 2y, and HE = 3x + 2. Find the values of x and y.

4) Square MNPQ is below. PQ = 19 and NP = 4x - 1. Find x and PA.

N P

M Q

A

5) Find xy. x y

20

18

Homework1. Worksheet on “Properties of

Parallelograms”.2. Worksheet on Properties of

Quadrilaterals.3. Worksheet on

Quadrilaterals.