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example 5: Find the perimeter of a square whose each side is 4.5 cm. 4.5 cm
Solution: Here, side of the square = 4.5 cm

Perimeter = 4 × side = 4 × 4.5 cm = 18 cm 4.5 cm
Thus, the perimeter of the square is 18 cm.

example 6: Find the side of a square sheet whose perimeter is 32 cm.
Solution: Given, perimeter of a square sheet = 32 cm

Since, perimeter of a square = 4 × side
Therefore, 32 cm = 4 × side

Thus, the side of the square sheet = 32 = 8 cm
4
example 7: If the cost of framing a picture is `3.5 per cm, then find the
cost of framing the squared shape picture whose side is 32 cm long.
Solution: Here, length of the side of a picture = 32 cm

Since, perimeter of square = 4 × side
= 4 × 32 cm = 128 cm

Now, the cost of framing a picture = `3.5 per cm
Therefore, the total cost of framing the picture = 128 × `3.5 = `448.

Think and Answer

What is the perimeter of your math textbook and notebooks? Also, which has a greater
perimeter and by how much?

perimeter of a triangle

In the given figure, ABC is a triangle whose sides are AB, BC and CA. A

Perimeter of DABC = AB + BC + CA
Perimeter of a triangle = Sum of its sides
B C
example 8: Find the perimeter of a triangle whose sides are 4 cm, 7 cm and 8 cm,

respectively.
Solution: Since,
Perimeter of the triangle = Sum of its all sides 7 cm 4 cm

= (4 cm + 7 cm + 8 cm)
= 19 cm 8 cm

example 9: Find the perimeter of an isosceles triangle in which each
of the equal sides is 6 cm and the third side is 5 cm.
Solution: Perimeter of the given triangle = Sum of its all sides 6 cm 6 cm

= (6 cm + 6 cm + 5 cm)
= 17 cm. 5 cm

214 Mathematics-5