A simple nomograph based on a general result from analytical geometry can be used to represent the solution of any problem in which the sum of reciprocals equals another reciprocal — that is, the equation that generates the hyperbolic function. One such relationship is the thin-lens formula often used in introductory physics courses. This discussion will show that the nomograph is necessarily consistent with both the ray diagram for a thin lens and the object-image distance relationship obtained in the typical introductory physics laboratory experiment to determine the focal length of a thin lens. It is also useful to display the focal length of the thin lens on the graph obtained in such an experiment.

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