You would take the answer of the square root problem and find the number that you can multiply by its self that would make that answer correct.
From what I can pick up from your problem statement, you want to know "<span>a similar charm has a diameter of 4 cm what is the circumference." Please, would you use proper punctuation in your writing, for greater clarity:
"A</span><span> similar charm has a diameter of 4 cm. What is the circumference?"
The formula for the circumference of a circle, when the diameter is known, is
C=</span>

d or C=pi*d
In this case, with diamter 4 cm, the circumference, C, is 4pi cm.
Is there a picture? I don't know how to answer without the actual problem. Sorry,
Answer:
The answer to your question is c = 20
Step-by-step explanation:
Data
a = 15
j = 24
k = 32
c = ?
Process
Use proportions to solve this problem. Compare the small triangle and the large triangle.
1.- Proportion of the small triangle
c/15
2.- Proportion of the large triangle
k/j
3.- Equal but terms and solve for c
c/15 = k/j
-Substitution
c / 15 = 32/24
c = 32(15)/24
-Result
c = 20
The answer is 6.35. Because you put in 254 / 40 and it says 6.35.