On a square handkerchief, nine circular designs each of radius 7 cm are made (see Fig. 12.29). Find the area of the remaining portion of the handkerchief.
From the figure, it can be observed that the side of the square is 42 cm
Area of square = (Side)2
= (42)2
= 1764 cm2
Area of each circle = πr2
= 
* (7)2
= 154 cm2
Area of 9 circles = 9 × 154
= 1386 cm2
Area of the remaining portion of the handkerchief = 1764 - 1386
= 378 cm2
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