The total length of the circle is calculated by the following formula:
Lenght = 2.π.r
As r = 4c
Then,
Lenght = 2.π.4
Lenght = 8π centimetrs
Now use the rule of 3
But we have to know:
...<..> ...
Then,
8π ________ 2π <= 360°
x ________ 3π
2π . x = 8π . 3π
x = (8π . 3π) / 2π
x = (8 . 3π)/ 2
x = 12π centimenters
x ~ 37,69 c