Explanation
The circumference of a circle describes the length of the circular line, i.e. the distance you cover when you walk once around the circle. The formula for the circumference of a circle is:
Procedure
To calculate the circumference of a circle, you need the radius (r) or the diameter (d). If you have been given the diameter, first divide it by 2 to get the radius. Then you put the radius into the circle circumference formula and calculate.
Examples
Calculate the circumference of a circle with radius r = 3\,\text{cm}.
Substitute the radius into the formula: U = 2 \cdot \pi \cdot 3 = 18.85\,\text{cm}.
Calculate the circumference of a circle with diameter d = 12\,\text{cm}.
First determine the radius: r = 12 : 2 = 6\,\text{cm}. Then calculate the circumference: U = 2 \cdot \pi \cdot 6 = 37.70\,\text{cm}.
Note
- ★The formula for the circumference of a circle is: U = 2 \cdot \pi \cdot r.
- ★Pay attention to whether radius or diameter is given. The radius is always half the diameter.
Exercises
Start now & improve your maths grades! 🚀
Cancel your trial online at any time