The radius of the circle, the length of which is 138.16 cm, was increased by 5 cm.

The radius of the circle, the length of which is 138.16 cm, was increased by 5 cm. How much did the length of this circle increase?

The length of a circle is equal to twice the product of its radius and the number Pi, which in this task must be taken as 3.14. From the initial circumference given to us, we find its radius:
138.16 / 2 / 3.14 = 22 cm.
The radius was increased by 5 cm, which means that it became equal to:
22 + 5 = 27 cm.
Let’s find the length of the circle again, but with a new radius (we will use the previously derived formula for this):
2 * 27 * 3.14 = 169.56.
Now let’s determine the difference between the resulting and the original circumference:
169.56 – 138.16 = 31.4.