# Q. 8.     Pragya wrapped a cord around a circular pipe of the radius $4\; cm$ (adjoining figure) and cut off the length required of the cord. Then she wrapped it around a square box of side $4\; cm$ (also shown). Did she have any cord left? $(\pi =3.14)$

R

It is given that the radius of the circle is 4 cm

We know that circumference of circle = $2 \pi r$

$\Rightarrow 2 \pi r = 2 \times 3.14 \times 4 = 25.12 \ cm$

And perimeter of the square is $= 4a$

$\Rightarrow 4a = 4 \times 4 = 16 \ cm$

Length of cord left is $= 25.12 - 16 = 9.12 \ cm$

Therefore, Length of cord left is  $9.12 \ cm$

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