## Geometry: Common Core (15th Edition)

$g$
All three triangles are similar to one another, meaning that the sides of the triangles are proportional. We can see that $j$ is the hypotenuse of the large triangle, and $d$ is one of the legs of that same triangle. Additionally, $d$ is the hypotenuse of one of the triangles formed by the altitude of the large triangle. What we want is the corresponding leg in this smaller triangle, which is represented by $g$. The proportion should read: $\frac{j}{d} = \frac{d}{g}$