Question

Find the circumference of a circle whose diameter is 21cm

Answer 1

Step-by-step explanation:

Diameter (d) = 21 cm

so, radius = d/2

r = 21/2

r = 10.5 cm

Circumference of a circle = 2πr

= 2 × 22/7 × 10.5

= 462/7

= 66 cm

Circumference of a circle = 66 cm

Answer 2

$\textbf{\huge\underline{\underline\red{Solution} : - }} \\ \\ \textbf{\underline{\underline\red{given} : - } diameter\: of \: circle \: is \: } \\ \textbf{21 \:cm.so\: radius \: is \: 10.5 \:cm} \\ \\ \textbf{\underline{\underline\red{formula} : - }} \\ \\ = > \bold \purple{circumference \: of \:circle \: = 2 \: \pi \: r } \\ \\= > \bold \purple{circumference \: of \:circle \: = 2 \times \frac{22}{7} \times10.5} \\ \\ = > \bold \purple{circumference \: of \:circle \: = \frac{22}{7} \times21 } \\ \\\bold \purple{circumference \: of \:circle \: = 22 \times 3} \\ \\ = > \bold \purple{circumference \: of \:circle \: = 66 \: cm } \\ \\ \bold{ \underline\red{hence \: circumference \: of \: circle \: is \: 66\: cm.}} \\ \\ \fcolorbox{red}{white}{i \: hope \: it \: helps \: you.}$