C
Q
WE SHALL LEARN HOW TO
CONSTRUCT A UNIQUE
QUADRILATERAL BY FOLLOWING
METHODS :-
When four sides and one diagonal are given.
When two diagonals and three sides are given.
When two adjacent sides and three angles are given.
When three sides and two included angles are given.
When other special properties are known.
CONSTRUCTING A QUADRILATERAL
WHEN FOUR SIDES AND ONE
DIAGONAL ARE GIVEN
Example : Construct a quadrilateral PQRS where PQ = 4cm, QR =
6cm, RS= 5cm, PS =
5.5cm and PR = 7cm
7 cm
Step 1 :-
Construct a triangle PQR using
SSS criterion.
7 cm
STEP 2 :-
WITH P AS CENTRE DRAW AN
ARC OF RADIUS 5.5 CM .
7 cm
STEP 3 :-
NOW, WITH R AS CENTRE DRAW AN
ARC OF RADIUS 5 CM INTERSECTING
ANOTHER ARC AT POINT S
7 cm
STEP 4 :-
NOW JOIN PS AND RS.
7 cm
PQRS is the required quadrilateral.
CONSTRUCTING A
QUADRILATERAL WHEN TWO
DIAGONALS AND THREE SIDES
ARE GIVEN.
Example : Construct a quadrilateral ABCD, given that BC =4.5 cm, AD = 5.5 cm, CD = 5 cm, AC = 5.5 cm and diagonal BD = 7 cm.
D
7 cm
A
C
B
STEP 1 :-
DRAW TRIANGLE ACD USING SSS
CRITERION
D
A
5.5 cm
C
STEP 2 :-
WITH D AS CENTRE DRAW AN
ARC OF RADIUS 7 CM.
D
A
5.5 cm
C
STEP 3 :-
NOW, WITH C AS CENTRE DRAW AN ARC
OF RADIUS 4.5 CM INTERSECTING
ANOTHER ARC AT POINT B.
D
A
5.5 cm
B
C
STEP 4 :-
JOIN AB, DB AND CB
D
A
5.5 cm
B
C
CONSTRUCTING A
QUADRILATERAL WHEN TWO
ADJACENT SIDES AND THREE
ANGLES ARE KNOWN
Example : Construct a M
120
quadrilate ral MIST where
MI
3.5
cm,
M
S
75
120
,
IS
6.5
cm,
I
105
and
T
105
I
75
S
Step 1 : -
Draw a line MI
3.5
cm and make an
MIX
105
.
X
M 3.5 cm
105
I
Step 2 : -
Measure IX
6 .
5 and name that point S.
Now make
ISY
120
.
Y
120
S
X
M 3.5 cm
105
I
Step 3 : -
Now make
IMZ
Z
75
Y
120
S
X
M
75
105
3.5 cm I
STEP 4 :-
MARK THAT POINT T WHERE SY AND MZ
MEET.
Y
T
Z
120
S
X
M
75
3.5 cm
105
I
MIST is the required
Quadrilateral .
CONSTRUCTING A
QUADRILATERAL WHEN
THREE SIDES AND TWO
INCLUDED DIAGONALS ARE
GIVEN.
Example : Construct a
D
Quadrilate ral ABCD, where
AB
4 cm, Bc
5 cm,
CD
6.5
cm,
B
105
and
C
80
.
A 4 cm
B
C
Step 1 : -
Draw a line BC
5 cm and Draw an
of 105
along BX.
X
B
105
5 cm C
Step 2 : -
Measure BX
4 cm and name that point A.
X
A
B
105
5 cm C
Step 3 : -
Now make
BCY
80
Y
X
B
105
5 cm
80
C
Step 4 : -
Now, with C as centre,
Draw an arc of length 6.5
cm that cuts CY at point D.
Y
D
X
B
105
5 cm
80
C
X
B
Step5 : -
Join AD
Y
105
5 cm
D
80
C
.
CONSTRUCTING A
QUADRILATERAL WHEN
OTHER SPECIAL PROPERTIES
ARE KNOWN.
Some examples are :-
1.
Draw a square of side 5 cm.
2.
Construct a rhombus ABCD where AC =
6 cm, and BD = 7 cm.
EXAMPLE 1 :-
DRAW AN SQUARE ABCD OF
SIDE 5 CM.
has been given. Actually we have many more details with us, because the figure is special quadrilateral namely a square. We know that each of its angles is a
Right angle.
D
90
90
4.5 cm
90
90
C
A 4.5 cm
B
EXAMPLE 2 :-
CONSTRUCT A RHOMBUS ABCD
WHERE AC = 6 CM, AND BD = 7 CM.
Rhombus are Perpendicular bisectors of one another.
D
So, first we draw AC = 7 cm and construct its perpendicular bisector. Let them meet at O. cut off
3 cm lengths on either side of the drawn bisector . You get now B and
D.
A O
7 cm
B
C