Question

Area of a circle is 154 cm square find it's circumference ​

Answer 1

Given :

• Area of circle = 154 cm²

To Find :

• Circumference of circle = ?

Formula used :

• Area of circle = πr²
• Circumference of circle = 2πr

Solution :

First of all we have to calculate the radius of circle :

Let radius of circle be 'r'

★ Finding radius of circle :

→ Area of circle = πr²

→ 154 = πr²

→ 154 = 22/7 × r²

→ 154 × 7/22 = r²

→ 49 = r²

→ r² = 49

→ r = √49

→ r = 7 cm

Hence,radius of circle is 7 cm.

★ Finding circumference of circle :

➻ Circumference of circle = 2πr

➻ Circumference of circle = 2 × 22/7 × 7

➻ Circumference of circle = 2 × 22

➻ Circumference of circle = 44 cm

Therefore,circumference of circle is 44 cm.

Answer 2

Given :

Area of circle is 154 cm²

To Find :

Circumference of circle

Solution :

Let the radius be ' r '

$\bigstar \: \large{\sf{\underline{\red{Area\:of\:Circle\:=\:π{r}^{2}}}}}$

$\leadsto \sf 154\:=\: \dfrac{22}{7} \times {r}^{2}$

$\leadsto \sf {r}^{2}\:=\: \dfrac{154 \times 7}{22}$

$\leadsto \sf {r}^{2}\:=\: \cancel \dfrac{1078}{22}$

$\leadsto \sf {r}^{2}\:=\:49$

$\leadsto \sf r\:=\: \sqrt{49}$

$\bigstar \: \large{\sf{\underline{Radius\:=\:7\:cm}}}$

$\bigstar \: \large{\sf{\underline{\red{Circumference\:of\:Circle\:=\:2πr}}}}$

$\leadsto \sf Circumference\:of\:circle\:=\:2 \times \dfrac{22}{7} \times 7$

$\leadsto \sf Circumference\:of\:circle\:=\: 2 \times 22 \times 2$

$\bigstar \: \large{\sf{\underline{\red{Circumference\:of\:circle\:=\:44\:cm}}}}$

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