Quadrilaterals is a polygon with four sides. Kinds of quadrilaterals are parallelogram, rectangle, rhombus, square, trapezoid, and trapezium.

1. Hello everyone!
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2. MATHEMATICS
9
Quarter 3:
Module 1
Part 1
QUADRILATERALS

3. QUADRILATERAL
Quadrilateral is a
polygon with four
sides.
A
B
C
D

4. Quadrilaterals
Around You

5. • A quadrilateral is named
by its consecutive sides.
• In the figure, the
quadrilateral is named
ABCD or BCDA or
CDAB or DABC.
A
B
C
D

6. • The quadrilateral has four
vertices namely A, B, C, and D.
• Vertices A and B, B and C, C and
D, and D and A are called
consecutive vertices.
• Vertices A and B, and C and D
are called opposite vertices.
A
B
C
D

7. • Two sides with a common
vertex, like 𝐴𝐵 and 𝐵𝐶, are
adjacent sides.
• On the other hand, 𝐴𝐵 and
𝐷𝐶 are opposite sides.
A
B
C
D

8. • Two angles with a common
side, like ∠A and ∠B, are
adjacent angles.
• On the other hand, ∠B and
∠D are opposite angles.
A
B
C
D

9. • Segments joining
opposite vertices, like
𝐴𝐶, is called diagonal
of the quadrilateral.
A
B
C
D

10.  The diagonals of a convex quadrilateral are contained entirely
inside of the figure.
 While in concave quadrilateral, one of the diagonal lie outside
the figure.
A
B
C
D
Convex Quadrilateral
E
H
F
G
Concave Quadrilateral

11. • Diagonals 𝐴𝐵 and 𝐵𝐶 of quadrilateral ABCD intersect.
• Diagonals 𝐴𝐵 and 𝐵𝐶 of quadrilateral EFGH do not intersect
A
B
C
D
Convex Quadrilateral
E
H
F
G
Concave Quadrilateral

12. KINDS
OF
QUADRILATERALS

13. Parallelogram
• It is a quadrilateral with two
pairs of parallel sides.
• ABCD is a parallelogram
with 𝐴𝐵║𝐷𝐶 and 𝐵𝐶║𝐴𝐷.

14. Note:
Right angles measures 90ᴼ.
E F
G
H
Rectangle
• It is a parallelogram with
four right angles.
• EFGH is a rectangle with
∠E, ∠F, ∠G, and ∠H that are
right angles.

15. Rhombus
• It is a parallelogram with four
congruent sides.
• MNOP is a rhombus with
MN ≅ NO ≅ OP ≅ PM.
M
P O
N

16. Square
• It is a rectangle with four
congruent sides.
• IJKL is a square with
ഥ
IJ ≅ ഥ
JK ≅ KL ≅ ഥ
LI, and ∠I, ∠J,
∠K, and ∠L are right angles.
J K
L
I
Note:
A square is both a rectangle
and a rhombus.

17. Trapezoid
• It is a quadrilateral with exactly one
pair of parallel side.
• QRST is a trapezoid with QR║TS. The
parallel sides are called the bases, and
the non-parallel sides are called the
legs.
• The angles on the bases of the
trapezoid are called base angles.
T
Q R
S
 The sides QR and TS are the
bases, and TQ and SR are the
legs. On the other hand, ∠T
and ∠S are called base angles,
and so are ∠Q and ∠R.

18. Isosceles Trapezoid
• It is a trapezoid with legs are
congruent.
• WXYZ is an isosceles
trapezoid with WX ≅ ZY.
X
W Z
Y

19. Trapezium
• It is a quadrilateral with no
parallel sides.
• ABCD is a trapezium.
A
B
C
D

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