ENTS,

     In a recent conversation with Will Blozan, Will and I discussed the desirability of including a variety of simple problems the solution to which should be second nature to the experienced Ent engaged in tree measuring. What we have in mind are straightforward application of right angle trigonometry . Problem #6, presented in the attachment,   is an example.

Bob

Problem #6: A measurer wants to determine the spread of the crown of a tree being measured. However, on one side of the tree, the end of the crown is inaccessible to the measurer (on private property, extends over a structure, etc.). The end of the crown is visible from the trunk. If the measurer has a laser and clinometer, standing at the trunk, how may he/she calculate the horizontal extension of the limb?

Solution: This is a simple problem for right angle trigonometry. The diagram below shows the calculation required.

Comments: We have used the cosine function to compute horizontal offset of the crown point, but the cosine function has many other uses. It is important to always keep in mind the relationships of sine, cosine, and tangent. They all have applications.