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?
i don't understand this.Help?? Thanks:)
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?
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
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!
The formula for the circumference of a circle is C = 2Ï€r, 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 = 2Ï€(9) = 18Ï€ 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 18Ï€ cm, and the circumference of a circle with a diameter of 9 cm as 9Ï€ 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.