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The circle with center O has a minor arc BSA with a length of

2 inches. The central angle is 40°. What is the circumference of the circle?
A)

2 inches
B)

2 inches
C)
13π
2 inches
D)
27π
2 inches
The answer is D

Respuesta :

Answer:

D. [tex]\frac{27\pi}{2}[/tex] inches.

Step-by-step explanation:

We have been given that the circle with center O has a minor arc BSA with a length of [tex]3\pi^{2}[/tex] inches. The central angle is 40°.

To find the circumference of circle we will use formula:

[tex]\frac{\text{Central angle}}{2\pi}=\frac{\text{Arc length}}{2\pi r}[/tex], where [tex]2\pi[/tex]= measure of 360 degrees in radians and [tex]2\pi r[/tex]= circumference of circle.  

Let us convert measure of central angle into radians.                        

[tex]40^{o}=\frac{40*\pi}{180} =\frac{2\pi}{9}[/tex]

Upon substituting our given value in the formula we will get,        

[tex]\frac{\frac{2\pi}{9}}{2\pi}=\frac{\frac{3\pi}{2}}{2\pi r}[/tex]

[tex]\frac{2\pi}{18\pi}=\frac{3\pi}{4\pi r}[/tex]    

[tex]\frac{1}{9}=\frac{3}{4r}[/tex]      

Cross multiplying we will get,      

[tex]4r=27[/tex]  

[tex]r=\frac{27}{4}[/tex]

Hence, the radius of our circle is 27/4 inches.  

Since the circumference of circle is [tex]2\pi r[/tex]. Upon substituting  [tex]r=\frac{27}{4}[/tex] we will get,

[tex]2\pi r=2\pi* \frac{27}{4}=\frac{27\pi}{2}[/tex]

Therefore, circumference of our given circle will be [tex]\frac{27\pi}{2}[/tex] inches and option D is the correct choice.

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