Shadow Method
Measuring Heights
              The method can be used only if the sun is able to cast a shadow. First is we measure the shadow cast by the tree (from the base of the tree to the shadow of it's top), we label this length as AB. We then measure the shadow cast by someone or an object of known height, we label this as CD.
                              
We merely solve the unknown height by use of proportions, by equating:
         AB KNOWN                 AB - Length of the shadow cast by tree
UNKNOWN = ----------------------, where
           CD               CD - Length of the shadow cast by a known height