Circumference: Applying the formula

Look at the circle in the figure:

Its radius is equal to 4.

What is its circumference?

The formula for the circumference is equal to:

$2\pi r$

8π

Look at the circle in the figure.

What is its circumference if its radius is equal to 6?

Formula of the circumference:

$P=2\pi r$

We insert the given data into the formula:

$P=2\times6\times\pi$

$P=12\pi$

$12\pi$

O is the center of the circle in the figure below.

What is its circumference?

We use the formula:$P=2\pi r$

We replace the data in the formula:$P=2\times8\pi$

$P=16\pi$

$16\pi$ cm

Look at the circle in the figure.

The radius of the circle is $\frac{2}{3}$.

What is its perimeter?

The radius is a straight line that extends from the center of the circle to its outer edge.

The radius is essential for calculating the circumference of the circle, according to the following formula:

If we substitute the radius we currently have, the formula will be:

2*π*2/3

Let's start solving, we'll rearrange the formula:

π*2*2/3 =

We'll multiply the fraction by the whole number:

π*(2*2)/3 =

π*4/3 =

4/3π

And that's the result!

$\frac{4}{3}\pi$

$r=2$

Calculate the circumference.

12.56

Given the circle whose radius has a length of 9 cm

What is its perimeter?

56.55

$r=6$

Calculate the circumference.

37.699

$r=7$

Calculate the circumference.

43.982

$r=11$

Calculate the circumference.

69.115

Look at the circle in the figure below.

The diameter of the circle is 4.

What is its perimeter?

$4\pi$

Look at the circle in the figure below.

The radius of the circle is equal to 8.

What is its perimeter?

$16\pi$

Look at the circle in the figure below.

The radius of the circle equals 7.

What is its perimeter?

$14\pi$

Look at the circle in the figure.

The diameter of the circle is 10.

What is its perimeter?

$10\pi$

A circle has a radius of 3 cm.

What is its perimeter?

$6\pi$ cm

Look at the circle in the figure.

Given that its radius is equal to 3, what is its circumference?

$6\pi$

O is the center of the circle in the diagram.

What is its perimeter?

$8\pi$ cm

Look at the circle in the figure.

The diameter of the circle is 12.

What is its perimeter?

$12\pi$

Look at the circle in the figure below.

The radius of the circle equals 5.

What is its perimeter?

$10\pi$

Look at the circle in the figure.

If its diameter is 5, then what is its circumference?

$5\pi$

$r=\frac{1}{3}$

Calculate the circumference.

2.094