The circumference difference between the two circles is 18.84 cm. How many cm is the radius difference?

The circumference difference between the two circles is 18.84 cm. How many cm is the radius difference?

Radius difference: 18.84 / 2 / 3.13 = 3cm

The sum of the circumference of the two circles is 18.84 cm. It is known that the radius of the big circle is twice that of the small circle. How many cm are the circumference of the two circles?

Let the radius of the small circle be x, then the big circle be 2x, and the formula is 3.14x (2x + 4x) = 18.84
14 x 2 = 6. 18, respectively
3.14x2x2=12.56

As shown in the figure, the circumference of the three equal circles is 18.84 cm. Find the area of the shadow part

A: the sum of the three shadow areas is 21.195 square centimeter