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Solution: Split the interior of the quadrilateral into unit squares.

A B

D E C

Count the number of whole squares and half squares inside the quadrilateral.
There are 22 unit squares and 4 half squares along the side BC

1
so the area is 22 + 4 × = 24 sq. units.
2
Example 20: Find the area of the quadrilateral ABCD given below.

A

D

C
B

Solution: Build a rectangle completely around the shape and count the F A
number of unit squares to find the area of the complete figure.
Area of rectangle AFEB = 12 sq. units D

C

E B
Now, chop the figure to get the area of the quadrilateral ABCD.
1
F G A Area of triangle AGD = of area of rectangle GAJD = 1 sq. unit
2
H J 1
D Area of triangle DHC = of area of rectangle HDKC = 1 sq. unit
2
C K L 1 3 1
Area of triangle CEB = of area of rectangle CLBE = = 1 sq. units
E B 2 2 2
Area of square FGDH = 1 sq. unit
 1 1
1
We have to chop 1 +++ 1 2 2
1
 sq. units = 4 sq. units.


 1
The area of the remaining figure, that is, the area of the quadrilateral (ABCD) = 12 − 4 2  sq. units


1
= 7 sq. units
2
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Mathematics-6
Mathematics-6 196