The circumference of a circle is [tex][tex]$36 \pi$[/tex][/tex] feet. What is the length of the radius of this circle?

A. [tex][tex]$9 ft$[/tex][/tex]
B. [tex][tex]$18 ft$[/tex][/tex]
C. [tex][tex]$36 ft$[/tex][/tex]
D. [tex][tex]$72 ft$[/tex][/tex]



Answer :

To determine the length of the radius of a circle given the circumference, we use the relationship between the circumference and the radius. The formula for the circumference ([tex]\(C\)[/tex]) of a circle is:

[tex]\[ C = 2 \pi r \][/tex]

where [tex]\(r\)[/tex] is the radius and [tex]\(\pi\)[/tex] is a constant approximately equal to 3.14159.

1. We're given the circumference [tex]\(C = 36 \pi\)[/tex] feet.
2. Substitute [tex]\(C\)[/tex] into the formula:
[tex]\[ 36 \pi = 2 \pi r \][/tex]

3. To solve for the radius [tex]\(r\)[/tex], divide both sides of the equation by [tex]\(2 \pi\)[/tex]:
[tex]\[ r = \frac{36 \pi}{2 \pi} \][/tex]

4. Simplify the fraction by canceling [tex]\(\pi\)[/tex] on both the numerator and the denominator:
[tex]\[ r = \frac{36}{2} \][/tex]

5. Calculate the resulting division:
[tex]\[ r = 18 \][/tex]

Therefore, the length of the radius of the circle is [tex]\(18\)[/tex] feet.

So the correct answer is:
[tex]\[ \boxed{18 \text{ ft}} \][/tex]

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