Question

find the radius of a circle whose circumference is 21

Answer 1

2 ×22/7×r=21
r=21×7/2×22
r=147/44

r = 3.3
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Answer 2

$\textbf{\huge\underline{\underline\red{Solution} : - }} \\ \\ \textbf{\underline{\underline\red{given} : - }circumference \: of \: circle \: is \: } \\ \textbf{ \: \: \: \: \: \: \: \: \:21 \:units. } \\ \\ \textbf{\underline{\underline\red{formula} : - }} \\ \\ = > \bold \purple{circumference \: of \:circle \: = 2 \: \pi \: r } \\ \\ = > \bold \purple{ 21 = 2 \times \frac{22}{7} \times r} \\ \\ = > \bold \purple{ \frac{21 \times 7}{22 \times 2} = r} \\ i.e. \\ = > \bold \purple{r = \frac{21 \times 7}{22 \times 2} } \\ \\ = > \bold \purple{ r = \frac{147}{44} } \\ \\ = > \bold \purple{r = 3.340909091 \: unit } \\ \\ = > \bold \purple{r = 3.34 \: unit} \\ \\ \bold{ \underline\red{hence \: radius \: of \: circle \: is \: 3.34 \: unit}} \\ \\ \fcolorbox{red}{white}{i \: hope \: it \: helps \: you.}$