Question

The area of a circle is 1386cm^ find its circumference

Answer 1

Answer: 2904/7 cm

Step-by-step explanation:

Area of a circle = πR²

πR² = 1386cm²

R² = 1386 x 22/7

R² = 198 x 22

R = √4356

R = 66 cm

Radius = 66 cm.

Circumference = 2πR

= 2 x 22/7 x 66

= 2904/7

Therefore, Circumference of circle = 2904/7 cm.

Answer 2

GIVEN:

• The area of a circle is 1386cm²

TO FIND:

• What is the circumference of the circle ?

SOLUTION:

Let the radius of the circle be 'r' cm

We know that the formula for finding the area of the circle is:-

$\large{\boxed{\bf{\star \: AREA = \pi r^2 \: \star}}}$

According to question:-

On putting the values in the formula, we get

Take π = 22/7

$\rm{\hookrightarrow 1386 = \dfrac{22}{7} \times r^2 }$

$\rm{\hookrightarrow 1386 \times 7 = 22 \times r^2 }$

$\rm{\hookrightarrow 9702 = 22 \times r^2 }$

$\rm{\hookrightarrow \cancel\dfrac{9702}{22} = r^2 }$

$\rm{\hookrightarrow 441 = r^2 }$

$\rm{\hookrightarrow \sqrt{441} = r }$

$\rm{\hookrightarrow 21 \: cm = r}$

Now, we have to find the circumference of the circle

We know that the formula for finding the circumference of the circle is:-

$\large{\boxed{\bf{\star \: Circumference = 2 \pi r \: \star}}}$

According to question:-

On putting the given values in the formula, we get

Take π = 22/7

$\rm{\hookrightarrow Circumference = 2 \times \dfrac{22}{7} \times 21 }$

$\rm{\hookrightarrow Circumference = 2 \times \dfrac{22}{\cancel{7}} \times \cancel{21}}$

$\rm{\hookrightarrow Circumference = 2 \times 22 \times 3}$

$\bf{\hookrightarrow Circumference = 143 \: cm }$

❝ Hence, the circumference of circle is 143 cm² ❞

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