An equation named for this function applies the D'Alembertian to this function to yield soliton solutions and is derived from the KleinÂ–Gordon equation.
An equation named for this function applies the D'Alembertian to this function to yield soliton solutions and is derived from the KleinÂ–Gordon equation. The wave functions for a particle in a box are all proportional to this function because it is zero at the boundaries of the box. This function is multiplied by i in De Moivre's theorem. The Taylor series for this trigonometric function has only odd powered terms. The index of refraction is multiplied by this function of the incident angle in Snell's law. For 10 points, name this trigonometric function, equal to the ratio of the opposite side to the hypotenuse. 
An equation named for this function applies the D'Alembertian to this function to yield soliton solutions and is derived from the KleinÂ–Gordon equation.
sine