Find, with an accuracy of millimeters, the length of a circle with a radius equal to: 2.5 cm, 10 cm.

Let’s start solving the problem by recalling the formula for calculating the circumference of a circle, if we know the length of its radius.

So, to calculate the circumference, we will apply the formula:

C = 2nR, where C is the circumference, R is the radius of the circle, and we will take the number n to within hundredths of 3.14.

Let’s start with a radius of 2.5cm = 25mm. Substitute the values into the formula and calculate:

C = 2 * 3.14 * 25 = 157 mm = 15.7 cm.

Likewise with a radius of 10 cm = 100 mm.

C = 2 * 3.14 * 100 = 628 mm = 62.8 cm.