Question

find the circumference of the inner and outer circles inner circle = 21cm and outer circles = 7cm​

Answer 1

Correct Question :-

• Find the circumference of the inner and the outer circles, shown in the adjoining figure. (Take π = 3.14)

Answer :-

• Circumference of Inner Circle = 87.92 cm
• Circumference of Outer Circle = 131.88 cm

Given :-

• Outer Radius = 21 cm
• Width of Area Excluding Inner Radius = 7 cm

To Find :-

• Circumference of Inner Circle = ?
• Circumference of Outer Circle = ?

Explanation :-

Let's Find the Circumference of Both Circles,

$\green { \boxed { \bf \bigstar \: Circumference \: of \: Circle = 2 \pi r \: cm \: \bigstar }}$

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$\bf 1. \: Radius \: of \: Outer \: Circle = 21 cm$

$\rm \leadsto Circumference = 2 \pi r$

$\rm \leadsto 2 \times 3.14 \times 21$

$\rm \leadsto 6.28 \times 21$

$\red { \underline { \boxed { \bf \leadsto 131.88 \: cm }}}$

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$\bf 2. \: Radius \: of \: Inner \: Circle = (21 - 7)cm = 14 \: cm$

$\rm \leadsto Circumference = 2 \pi r$

$\rm \leadsto 2 \times 3.14 \times 14$

$\rm \leadsto 6.28 \times 14$

$\red { \underline { \boxed { \bf \leadsto 87.92 \: cm }}}$

_____________________

Hence, the Circumference of the Both Circles are 131.88 cm and 87.92 cm Respectively.