The French Academy of Sciences said that a quarter of the earth’s circumference is 10 000 000 m. The definition of $\pi$ is: $\pi=\frac{C}{d}$ We can re-arrange and divide both sides by 4 to get: $\frac{C}{4}=\frac{\pi r}{2}$ The French _defined_ $\frac{C}{4}=10,000 \text{ km}$ so we can now solve for the radius: $r=10,000\cdot\frac{2}{\pi}=3,266\text{ km}$ ### Resources: - [https://www.youtube.com/watch?v=Nbtnn2Mi2y4&list=PLGvhNIiu1ubyEOJga50LJMzVXtbUq6CPo&index=38&ab_channel=LaintalAy](https://www.youtube.com/watch?v=Nbtnn2Mi2y4&list=PLGvhNIiu1ubyEOJga50LJMzVXtbUq6CPo&index=38&ab_channel=LaintalAy) ![[Connect#Connect]]