Question

Find the area and the circumference of the circle
diameter=21 cm​

Answer 1

Answer:

Area = 346.5 cm²

Circumference / perimeter = 66 cm

Step-by-step explanation:

Area = πr²

Circumference = 2πr

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Answer 2

Answer:

The Area of the circle is $346.185\:cm^{2}$ and The circumference of the circle is 65.94 cm .

Step-by-step explanation:

Given -

Diameter= $21$ cm​

To find -

The area and the circumference of the circle

Solution-

Radius is half of diameter.

Diameter=$21$ cm​

Radius (r) = $\frac{21}{2} = 10.5$ cm

As, we know that

The circumference of the circle

$C=2\pi r$

Where,

C = Circumference of the circle

r =Radius

Put the given value in a formula

$C = 2\times \pi \times 10.5$

The value of $\pi$ is $3.14$

$C = 2\times 3.14 \times 10.5$

$C = 65.94\: cm$

The Area of the circle (A)

$A=\pi r^{2}$

Put the given value in a formula

$A = \pi 10.5^{2}$

$A =3.14 \times 10.5^{2}$

$A =3.14 \times 10.5\times10.5$

$A = 3.14\times 110.25$

$A = 346.185\:cm^{2}$

∴ The Area of the circle is $346.185\:cm^{2}$ and The circumference of the circle is 65.94 cm