Question

find the area of a circle whose circumference is 40 cm​

Answer 1

Answer:

• Area of circle = 127.13 cm²

Step-by-step explanation:

Given that:

• Circumference of a circle = 40 cm

To find:

• Area of a circle.

Solution:

Concept:

We will calculate the radius of a circle first by using the formula to calculate the circumference of a circle because we are already provided with the circumference then by using formula to calculate area of a circle we can easily find the area of circle.

Let's find out:

❖ Circumference of a circle = 2πr

⟹ 40 = 2 × 22/7 × r

⟹ 40 = 44/7 × r

⟹ r = (40 × 7)/44

⟹ r = 280/44

⟹ r = 6.36

∴ Radius = 6.36 cm

❖ Area of a circle = πr² sq. unit

⟹ Area of a circle = 22/7 × (6.36)² cm²

⟹ Area of a circle = 22/7 × 6.36 × 6.36 cm²

⟹ Area of a circle = 127.13 cm²

∴ The area of a circle = 127.13 cm²

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Answer 2

Answer:

Area of circle is 127.01 sq cm

Step-by-step explanation:

Given that

Circumference of circle is 40cm

To find

Area of circle

Solution

As we know that

$circumference \: of \: circle = 2\pi \times radius$

hence

$radius = \frac{circumference}{2\pi}$

put

$\pi = 3.14$

hence

$radius = \frac{40}{2 \times 3.14} = 6.36cm$

now

$area \: of \: circle = \pi \times {radius}^{2}$

$area \: of \: circle = 3.14 \times {6.36}^{2}$

$area \: of \: circle = 127.01 {cm}^{2}$