In Christen hypsometer, find length bd for a tree of 24 m height when BD (staff length) is 4 m and ab (distance between the flanges) is 33 cm.

Correct Answer: (D) 5.50 cm

In a Christen hypsometer, by similar triangles, the relationship is $\frac{bd}{ab}=\frac{BD}{AB}$$\frac{bd}{ab}$ = $\frac{BD}{AB}$, where $ab = 33$$\text{ cm}$ is the distance between flanges, $BD = 4$$\text{ m}$ is the staff length, and $AB = 24$$\text{ m}$ is the tree height. Thus, $bd = 33$$\times$ $\frac{4}{24}$ = $\frac{33}{6}$ = 5.50 $\text{ cm}$.