Analysis of test questions: similar triangles can be constructed according to the meaning of the questions and solved according to the nature of similar triangles.

(1) The required measuring tools are: tape measure and benchmark;

(2) The measurement schematic diagram is as follows:

(3) As shown in the figure, the measured benchmark de = a,

The shadow lengths of the tree and the benchmark are AC = b and ef = c, respectively.

From △DEF∽△BAC, we get

∴ ,?

∴ .

Comments: The application of similar triangles is the focus of junior high school mathematics, which runs through the whole junior high school mathematics study. It is a common knowledge point in the senior high school entrance examination, which is generally not difficult and needs to be mastered skillfully.