1. Rhombus and Square

2. Goals Define rhombus. Discuss properties.
Define square. Discuss properties.
Use properties to determine if a quadrilateral is a parallelogram, rectangle, rhombus, square.

3. Properties of a Parallelogram
Definition: Both pairs opp. sides of are parallel.
Both pairs opp. sides are congruent
Both pairs opp. angles are congruent
All consecutive angles add to 180.
Diagonals bisect each other.
One pair of sides is parallel and congruent.
REVIEW !!
Characteristics of a Rectangle
See above
Definition: All four angles are congruent
Diagonals are congruent.

4. Rhombus - Definition
The plural of rhombus is “rhombi”
A rhombus is a parallelogram where all 4 sides are congruent.
The characteristics of parallelograms are also true for rhombus, since it is a special type of parallelogram.

5. What is the relationship between AC and BD?
Rhombus - Diagonals
The diagonals of a rhombus are perpendicular. A
What is the relationship between AC and BD? D B C

6. Rhombus - Diagonals
If the diagonals of a parallelogram are perpendicular, then it is a rhombus. A
If AC is perpendicular to BD and ABCD is a parallelogram, then ABCD is a rhombus D B C

7. Rhombus – Diagonals - Angles
The diagonals of a rhombus bisect the opposite angles. A D B C

8. Square - Definition
A square is a parallelogram where all 4 angles are congruent and all four sides are congruent.
A square has all the same properties as a parallelogram, a rhombus, and a rectangle.

9. Parallelograms Both pairs opp. sides of are parallel.
Both pairs opp. sides are congruent
Both pairs opp. angles are congruent
All consecutive angles add to 180.
Diagonals bisect each other.
One pair of sides is parallel and congruent.
Rectangles
All four angles are congruent
Diagonals are congruent.
ALL parallelogram properties.
Rhombi
All four sides are congruent
Diagonals are perpendicular.
Opp. angles are bisected.
Squares
The only regular quadrilateral.
ALL properties of para, rect, and rhom.
I’m thinking of a quadrilateral where all the sides are equal… what could it be?
Rhombus or Square
I’m thinking of a quadrilateral where the opposite sides are parallel… what could it be?
Para, Rect, Rhom, or Square

10. Parallelograms Best Name?? Both pairs opp. sides of are parallel.
Both pairs opp. sides are congruent
Both pairs opp. angles are congruent
All consecutive angles add to 180.
Diagonals bisect each other.
One pair of sides is parallel and congruent.
Rectangles
All four angles are congruent
Diagonals are congruent.
ALL parallelogram properties.
Rhombi
All four sides are congruent
Diagonals are perpendicular.
Opp. angles are bisected.
Squares
The only regular quadrilateral.
ALL properties of para, rect, and rhom.
Best Name??

11. Parallelograms Best Name?? Both pairs opp. sides of are parallel.
Both pairs opp. sides are congruent
Both pairs opp. angles are congruent
All consecutive angles add to 180.
Diagonals bisect each other.
One pair of sides is parallel and congruent.
Rectangles
All four angles are congruent
Diagonals are congruent.
ALL parallelogram properties.
Rhombi
All four sides are congruent
Diagonals are perpendicular.
Opp. angles are bisected.
Squares
The only regular quadrilateral.
ALL properties of para, rect, and rhom.
Best Name??

12. Parallelograms Best Name?? Both pairs opp. sides of are parallel.
Both pairs opp. sides are congruent
Both pairs opp. angles are congruent
All consecutive angles add to 180.
Diagonals bisect each other.
One pair of sides is parallel and congruent.
Rectangles
All four angles are congruent
Diagonals are congruent.
ALL parallelogram properties.
Rhombi
All four sides are congruent
Diagonals are perpendicular.
Opp. angles are bisected.
Squares
The only regular quadrilateral.
ALL properties of para, rect, and rhom.
Best Name??

13. Caution! What could this be? What’s the best name?
There is a difference between…
What could this be?
What’s the best name?
It COULD be a parallelogram or a rectangle.
All we know FOR SURE is that it is a parallelogram.

14. The diagonals are congruent.
Match the property with all of the types of quadrilateral which have that property.
The diagonals are congruent.
Parallelogram
Rectangle
Rhombus
Square

15. Both pairs of opposite sides are congruent.
Match the property with all of the types of quadrilateral which have that property.
Both pairs of opposite sides are congruent.
Parallelogram
Rectangle
Rhombus
Square

16. Parallelograms Both pairs opp. sides of are parallel.
Both pairs opp. sides are congruent
Both pairs opp. angles are congruent
All consecutive angles add to 180.
Diagonals bisect each other.
One pair of sides is parallel and congruent.
Rectangles
All four angles are congruent
Diagonals are congruent.
ALL parallelogram properties.
Rhombi
All four sides are congruent
Diagonals are perpendicular.
Opp. angles are bisected.
Squares
The only regular quadrilateral.
ALL properties of para, rect, and rhom.

17. Quadrilaterals Parallelograms Rectangle Rhombus Square
4 sides, angles add to 360
Parallelograms
Opp sides parallel, Opp sides congruent, Opp angles congruent, Consecutive angles =180, Diagonals bisect
Rectangle
All angles are congruent.
Diagonals are congruent.
Rhombus
All sides are congruent.
Diagonals are perpendicular.
Opp angles are bisected.
Square
Everything