Question

The area of a circle is 15400 m square. Find its circumference.
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Answer 1

Answer:

Area of circle = pie × radius²

= 15400 m²

pie × radius² = 15400 m²

22/7 × r² = 15400

r² = (15400 × 7)/22

r² = 4900

r² = (70)²

r = 70 m

Radius of circle = 70 m

Circumference of circle = 2 × pie × radius

= 2 × 22/7 × 70

= 2 × 22 × 10

= 44 × 10

= 440 m

Answer 2

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Given -

Area of circle i.e 15400 m²

To find -

Its circumference.

Area of circle =

$\pi {r}^{2}$

$\pi {r}^{2} = 15400 \\ = {r}^{2} = \frac{15400 \times 7}{22} \\ = {r}^{2} = 4900 \\ = r = \sqrt{4900} \\ = 70 \: m$

Radius of circle = 70 m

Circumference of circle =

$2\pi \: r$

Therefore circumference of circle =

$2\pi \: r \\ = 2 \times \frac{22}{7} \times 70 \\ = 440 \: m$

Therefore circumference of circle is 440 m.