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This applet demonstrates how each of a collection of 8 periodic waveform graphs can built up from a sequence of trigonometrical curves. First choose your waveform. Then you can add one item at a time a sequence of cosine or sine curves that will match the waveform increasingly closely.

Software/Applets used on this page

This applet was produced by Dr. Constantinos E. Efstathiou at the Laboratory of Analytical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens and used with his permission.



The trigonometrical function defined as adjacent/hypotenuse in a right-angled triangle.


a function that repeats the same values over and over again.


a number pattern in a definite order following a certain rule


The trigonometrical function defined as opposite/hypotenuse in a right-angled triangle.

Full Glossary List

This question appears in the following syllabi:

SyllabusModuleSectionTopicExam Year
Methods (UK)M13Fourier seriesPeriodic graphs-
Universal (all site questions)FFourier seriesPeriodic graphs-