1. 6.4 Rhombuses, Rectangles, and Squares

2. Review Find the value of the variables. p + 50° + (2p – 14)° = 180°
52°
(2p-14)°
50°
68°
p + 50° + (2p – 14)° = 180°
p + 2p + 50° - 14° = 180°
3p ° = 180°
3p = 144 °
p = 48 °
52° + 68° + h = 180°
120° + h = 180 °
h = 60°

3. Special Parallelograms
Rhombus
A rhombus is a parallelogram with four congruent sides.

4. Special Parallelograms
Rectangle
A rectangle is a parallelogram with four right angles.

5. Special Parallelogram
Square
A square is a parallelogram with four congruent sides and four right angles.

6. Corollaries Rhombus corollary Rectangle corollary Square corollary
A quadrilateral is a rhombus if and only if it has four congruent sides.
Rectangle corollary
A quadrilateral is a rectangle if and only if it has four right angles.
Square corollary
A quadrilateral is a square if and only if it is a rhombus and a rectangle.

7. Example PQRS is a rhombus. What is the value of b? 2b + 3 = 5b – 6

8. Review In rectangle ABCD, if AB = 7f – 3 and CD = 4f + 9, then f = ___1 2 3 4 5
7f – 3 = 4f + 9
3f – 3 = 9
3f = 12
f = 4

9. Example PQRS is a rhombus. What is the value of b? 3b + 12 = 5b – 6

10. Theorems for rhombus
A parallelogram is a rhombus if and only if its diagonals are perpendicular.
A parallelogram is a rhombus if and only if each diagonal bisects a pair of opposite angles. L

11. Theorem of rectangle
A parallelogram is a rectangle if and only if its diagonals are congruent. A B D C

12. Match the properties of a quadrilateral
The diagonals are congruent
Both pairs of opposite sides are congruent
Both pairs of opposite sides are parallel
All angles are congruent
All sides are congruent
Diagonals bisect the angles
Parallelogram
Rectangle
Rhombus
Square
B,D
A,B,C,D
A,B,C,D
B,D
C,D C

13. Decide if the statement is sometimes, always, or never true.
A rhombus is equilateral.
2. The diagonals of a rectangle are _|_.
3. The opposite angles of a rhombus are supplementary.
4. A square is a rectangle.
5. The diagonals of a rectangle bisect each other.
6. The consecutive angles of a square are supplementary.
Always
Sometimes
Sometimes
Always
Always
Always
Quadrilateral ABCD is Rhombus.
7. If m <BAE = 32o, find m<ECD.
8. If m<EDC = 43o, find m<CBA.
9. If m<EAB = 57o, find m<ADC.
10. If m<BEC = (3x -15)o, solve for x.
11. If m<ADE = ((5x – 8)o and m<CBE = (3x +24)o, solve for x
12. If m<BAD = (4x + 14)o and m<ABC = (2x + 10)o, solve for x.
A B E
D C
32o
86o
66o
35o 16 26

14. Coordinate Proofs Using the Properties of Rhombuses, Rectangles and Squares
Using the distance formula and slope, how can we determine the specific shape of a parallelogram?
Rhombus –
Rectangle –
Square -
1. Show all sides are equal distance
2. Show all diagonals are perpendicular.
1. Show diagonals are equal distance
2. Show opposite sides are perpendicular
Show one of the above four ways.
Based on the following Coordinate values, determine if each parallelogram
is a rhombus, a rectangle, or square.
P (-2, 3) P(-4, 0)
Q(-2, -4) Q(3, 7)
R(2, -4) R(6, 4)
S(2, 3) S(-1, -3)
RECTANGLE
RECTANGLE