We can use trigonometry to solve the problem. First draw a picture of the situation to understand what is going on (See the attached photo).
Next, we can use the tangent function to solve for the height of the building:
[tex]tan(29^{\circ})= \frac{h}{71} [/tex]
Next, rearrange the problem to solve for h:
[tex]h = 71tan(29^{\circ})[/tex]
h = 39.356 ft