Question

What is the diameter of a circle with a 66 inch circumference??

Answer 1

$C = 2\pi r\\\\\frac{C}{2\pi } = \frac{2\pi r }{2\pi } \\\\\frac{C}{2\pi } = r\\\\\\\frac{66}{2\pi } = r\\\\21.01 = r$

Therefore, the diameter of the circle is about 21.01 in.