The circumference of the outside of a ring is 66 mm and it has an outer diameter of 21 mm so if the circumference of the inside the ring is 50 mm what is the inner diameter of the rain?

Step-by-step explanation:

The circumference of the outside of a ring is 66 mm and it has an outer diameter of 21 mm. The difference between the outer diameter and the inner diameter of the ring is its thickness. The thickness is constant around the ring. This means that inner outer and circles of the ring are similar. Therefore

Ratio of the outer diameter of the ring to the outer circumference of the ring = ratio of the inner diameter of the ring to the inner circumference of the ring. Therefore

21/66 = inner diameter/50

66× inner diameter = 50 × 21

Inner diameter = 1050/66 = 15.91mm

The inner diameter of the ring is 16 mm.

Step-by-step explanation:

As we know that ,

Circumference of a circle = , where d = diameter of the circle .

We are given that ,

The circumference of the outside of a ring is 66 mm and it has an outer diameter of 21 mm .

Now , if circumference of the inside the ring is 50 mm, then we have

, where d= diameter of the inner circle .

Then ,

Hence , the inner diameter of the ring is 16 mm.