The inverse relationship between wavelength and frequency can be represented graphically using geometric relationships. The right triangle provides a particularly useful mode of presentation as it allows the inverse proportional relationship to be expressed using geometric and/or trigonometric relationships. The basic relationship using SI units is illustrated in the TrianglePair-SI.pdf item. http://www.vip.ocsnet.net/~ancient/TrianglePair-SI.pdf The constant of proportionality is the product of the hypotenuse of one triangle and the vertical leg of the other. When the products of both pairs are equal the triangles are mutual, one is the inverse of the other. I know the relationship between wavelength and frequency is quite simple in its algebraic form, but the geometric form allows it to be expressed using angular relationships. The geometric form readily identifies a few features that are not easily envisioned in other forms.