It is known that the radius ratio of the two circles is 3:5, and the difference between the circumference of the two circles is 12.56 decimeters

It is known that the radius ratio of the two circles is 3:5, and the difference between the circumference of the two circles is 12.56 decimeters

The radius ratio of the two circles is equal to the perimeter ratio of the two circles, so the perimeter ratio of the two circles is also 3:5. The perimeter difference between the two circles is 5-3 = 2 parts, so each part is 12.56 △ 2 = 6.28 decimeters, so the perimeter of the big circle is 6.28 × 5 = 31.4 decimeters, and that of the small circle is 6.28 × 3 = 18.84 decimeters