For this case we have the following equation:
[tex] C = 2\pir [/tex]
From here, we clear the value of r:
[tex] r = \frac{C}{2\pi} [/tex]
Substituting the values in the obtained equation we have:
[tex] r = \frac{15}{2\pi} [/tex]
Doing the calculations we have:
[tex] r = 2.4 [/tex]
Answer:
The value of r is given by:
[tex] r = 2.4 [/tex]
