Okay, let’s check the easy approach.
C=Circunference=2pi*r
We can arrange that as r=C/(2pi)
Okay, we know what the radius is. Nice!
Now, let’s take a look at the formula of the area. Just because we can.
A=Area=pi*r^2
Wait! If we get the radius, we can get the A! Wait again! We just found the radius! What a crazy random happen-stance!
It almost looks planned.
So, if you substitute the radius, you get
A=pi*[C/(2pi)]^2
And that’s it. Cool.
