1. Chapter 5: Quadrilaterals
Chapter 5: Quadrilaterals
5-1: Parallelograms

2. Review of quadrilaterals
What is a quadrilateral?
What is the sum of the interior angles for a quadrilateral?
What are some quadrilaterals with special names?

3. What is a regular quadrilateral better known as?
What is a regular quadrilateral better known as?

4. Parallelograms Definition
Definition
a quadrilateral with both pairs of opposite sides parallel
We write it as ABCD (go clockwise).

5. Opposite sides of a parallelogram are congruent.
Theorem 5-1
Opposite sides of a parallelogram are congruent.

6. Opposite angles of a parallelogram are congruent.
Theorem 5-2
Opposite angles of a parallelogram are congruent.

7. Diagonals of a parallelogram bisect each other.
Theorem 5-3
Diagonals of a parallelogram bisect each other.
Diagonals of a parallelogram create congruent triangles.

8. What kind of special angles are A & B?
What kind of special angles are B & C? A B D C
In a parallelogram, consecutive angles are___, while opposite angles are___.

9. If LMNO is a parallelogram, then find a, b, x, & ya 45
y =
a =
b =
x = b 9 12 35 x y M N L O
y =
a =
b =
x = b a 6 8 80 x y M N L O

10. Find x & y for PINE y = x = I P E N y = x = I P E N 11x (4y+5) 18 2222 18
y =
x =
2x+8
(4y-2) I P E N 45
y =
x = 80
11x
(4y+5) I P E N

11. Find the perimeter of PINE, if PI=13 & IN = 18
Find the perimeter of PINE, if PI=13 & IN = 18
Find x & y for PINE P
4x-3y I
2x-y 5 E N 9
x =
y =

12. True or False Every parallelogram is a quadrilateral.
Every parallelogram is a quadrilateral.
Every quadrilateral is a parallelogram.
All angles of a parallelogram are congruent.
All sides of a parallelogram are congruent.
In RSTU,
In ABCD, if
In WXYZ,
In ABCD,

13. Can you name 6 properties (actually, 5 properties and one definition) of parallelograms?

14. Section 5.1 Classroom Exercises (p. 168) #3-8 & 16
Homework
Section 5.1 Classroom Exercises (p. 168) #3-8 & 16
Section 5.1 Written Exercises (p ) #5-12, 16, & 19-30