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5. Find the area of triangle in each figure.

(a) (b) (c) (d)

6. Find the area of a square whose perimeter is 120 m.

7. A rectangular plot has an area equal to 2550 sq. m. Its length is 75 m. Find the
breadth of the rectangular plot.
8. Find the area of a rectangle whose length is 24 m and perimeter is 88 m.

9. The length and breadth of a rectangular hall are 650 cm and 450 cm, respectively.
Find the cost of flooring it at the rate of `30 per sq. m.

10. Find the area of the following.

(a) 9 cm (b) 5 cm 5 cm (c) 9 cm
7 cm
8 cm 7 cm
2 cm 16 cm

5 cm
5 cm
14 cm 6 cm
7 cm

AreA of irregUlAr ShApeS

Let us find the area of the adjoining figure.
To find the area of closed figures on the squared paper, we follow the given steps:

Step 1: Count the number of squares of unit length which are completely enclosed by the
figure. In the figure, number of complete squares, m = 55

Step 2: Count the number of squares of unit length which are more than half part enclosed
by the closed figure.

Here, number of more than half squares, n = 8.
Step 3: Count the number of those squares which are

enclosed exactly half by the figure and divide the
number by 2.

Number of half squares, p = 5.
Step 4: Ignore those squares which are not enclosed less

than half by the figure.

Step 5: Add the total squares of steps 1, 2 and 3 to obtain the area of the complete figure.

222 Mathematics-5