
Perimeter = 2a + 2b
= 2 (a + b)
Example 1:
A parallelogram has sides measuring 20cm by 25cm. What is the Perimeter?
Solution

a = 20cm
b = 25cm
Perimeter = 2 (a + b)
Perimeter = 2(20 + 25)
= 2(45)
= 2 × 45
= 90cm
Example 2:
A parallelogram has sides measuring 250mm by 200mm. What would be the length of the side of a square having the same perimeter?
Solution:

Length of the parallelogram = 250mm
Breadth/Width of the parallelogram = 200mm
Perimeter p = 2 (a + b)
P = 2 (250 + 200)
P = 2(450)
P = 900 mm
Therefore the perimeter of the square = 900 mm (i.e. the same as the perimeter of the parallelogram).
But the perimeter of a square is
P = 4 × length
i.e. 900 = 4 × length
Divide both sides by 4
\( \frac{900}{4} = \frac{4 \: \times \: length}{4} \)Length = \( \frac{900}{4}\)
Length = 225m
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