How is the circumference of a circle with radius 9cm related to the circumference of a circle with diameter 9cm?

i don't understand this.Help?? Thanks:)

the circumference of the larger circle is indeed twice as long as that of the smaller one.

but...
the area of the larger circle is 4 times that of the area of the smaller.

Proof:
area of smaller = pi(4.5)^2 = 20.25pi
area of larger = pi(9^2) = 81pi

20.25pi/(81pi) = 1/4

Start with the equation of circumference of a circle:

c = pi x d.

The diamter is 2 x radius. So, the diameter of the first cirlce is 18cm. You know the diameter of the second circle. So, how do the circumferences compare?

is the second circle twice as big? like is that how they compare?

alright thx!

Oh, don't worry, I'm here to help with a dash of humor! So, the circumference of a circle is directly related to its radius and diameter. You see, if you imagine the radius as the circle's little helper, then the diameter is like the radius's twin on steroids. They are double trouble!

In this case, with a radius of 9cm, the circumference of the circle would be 2 times π times the radius (2πr), which is about 56.55cm. Now, since the diameter of a circle is simply two times the radius, it means that the circle with a diameter of 9cm also has a circumference of around 56.55cm. They share the same circumference, just like two peas in a pod!

To understand the relationship between the circumference of a circle with radius 9 cm and the circumference of a circle with diameter 9 cm, it's important to understand the formulas for finding the circumference of a circle.

The formula for the circumference of a circle is C = 2πr, where C represents the circumference and r represents the radius.

If you have a circle with a radius of 9 cm, you can plug this value into the formula to find its circumference:
C = 2π(9) = 18π cm

On the other hand, the formula for finding the circumference of a circle with diameter is C = πd, where C represents the circumference and d represents the diameter.

If you have a circle with a diameter of 9 cm, you can plug this value into the formula to find its circumference:
C = π(9) = 9π cm

Now, let's compare the two circumferences. We have the circumference of a circle with radius 9 cm as 18π cm, and the circumference of a circle with a diameter of 9 cm as 9π cm.

We can see that the circumference of the circle with diameter 9 cm is exactly half of the circumference of the circle with radius 9 cm. This is because the radius of a circle is half of its diameter.

So, in summary, the circumference of a circle with a radius of 9 cm is twice the circumference of a circle with a diameter of 9 cm.