Calculate Circle Circumference: Given Radius r=6 Units

There are two formulas: $C = 2\pi r$ (using radius) and $C = \pi d$ (using diameter). Since diameter = 2 × radius, both give the same result when used correctly!

It depends on what the question asks for! $12\pi$ is the exact answer, while 37.699 is the approximate decimal. Multiple choice questions usually want the decimal approximation.

For most problems, $\pi \approx 3.14159$ gives enough precision. Using more decimal places won't significantly change your final answer for typical geometry problems.

The area formula is $A = \pi r^2$, which would give $\pi \times 6^2 = 36\pi \approx 113.1$. This is much larger than circumference! Circumference measures the border, area measures the inside space.

Think of it this way: Circumference is like a fence around a circular yard - you're measuring the border distance. Use $C = 2\pi r$ or $C = \pi d$ depending on what measurement you're given.