How do you find the circumference of a circle from its diameter? This interactive tool lets you adjust the diameter of a circle and measure its circumference. There are two sliders: diameter slider, drag left or right to set the circle’s diameter; rolling/rotation slider, drag left or right to roll the circle.
Here’s how to use the tool and answer the questions:
- Set the circle’s diameter using the diameter slider. Then roll the circle until it completes 100% of a full rotation.
- Measure the circumference by seeing how far the circle has rolled. In other words, measure the length of the orange line after the circle rolls 100%.
- Repeat steps 1 and 2 several times, and record the diameter (d) and circumference (C) in the table below. Observe the graph of diameter vs. circumference that forms.
Using the data you collected, answer these questions:
What is the circumference of a circle with a diameter of 12? In general, what is the circumference of a circle with diameter d?
Have fun!