What geometric property relates the diagonal length ($d$) to the side length ($s$) in a regular pentagon?

Answer

The ratio $d/s$ is precisely equal to the Golden Ratio, $\phi$

In a regular pentagon, the ratio of the length of any diagonal to the length of any side is exactly equal to the Golden Ratio, $\phi$.

What geometric property relates the diagonal length ($d$) to the side length ($s$) in a regular pentagon?
Geometryshapepentagonpolygonregular