Question

Find the circumference of a circle, whose diameter is 21 cm

Answer 1

answer : circumference of circle = 2πr

radius = diameter /2

radius = 21/2

put values in formula= 2*22/7 * 21/2

= 66 cm

circumference of circle is 66 cm.

Answer 2

Given :-

• Diameter = 21 cm

To Find :-

• Circumference = ?

Solution :-

$\begin{gathered} \\ \large \; \bigstar \: \: \sf \pink{Circumference \: _{Circle} \: = \: \pi \times Diameter} \\ \\ \end{gathered}$

$\begin{gathered} \\ \longmapsto \: \: \sf{Circumference \: = \: \dfrac{22}{7} \: \times \: 21 } \\ \\ \end{gathered}$

$\begin{gathered} \\ \longmapsto \: \: \sf{Circumference \: = \: \dfrac{22 \times 21}{7} } \\ \\ \end{gathered}$

$\begin{gathered} \longmapsto \: \: \sf{Circumference \: = \: \dfrac{462}{7}} \\ \end{gathered}$

$\begin{gathered} \\ \longmapsto \: \: { \underline{\boxed{ \purple{\pmb{ \frak{Circumference = 66 cm}}}}}} \\ \\ \end{gathered}$

Hence :-

• Circumference = 66 cm

$\underline {\rule {250pt}{6pt}}$