What is the radius of a circle with a circumference of 22?

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Answer 1 · 2015-11-10T21:07:37

Approximately $\frac{7}{2}$ $7/2$ , exactly $\frac{11}{π}$ $11/pi$

The circumference of a circle is of length $2 π r$ $2pi r$ where $r$ $r$ is the radius.

So in our case

$22 = 2 π r$ $22 = 2 pi r$

Divide both sides by $2 π$ $2 pi$ to get:

$r = \frac{22}{2 π} = \frac{11}{π}$ $r = 22 / (2 pi) = 11/pi$

One well know approximation for $π$ $pi$ is $\frac{22}{7}$ $22/7$ , which gives the approximation:

$r \approx \frac{11}{\frac{22}{7}} = \frac{7}{2}$ $r ~~ 11/(22/7) = 7/2$