Tangent graph: Animation of a tangent graph (y = tan x). These are produced when the tangent value (the sine divided by the cosine) is mapped to the y-axis and the rotation along the x-axis. This animation illustrates the relationship between a circle (the wheel in this movie) and the appearance of the tangent graph. As the wheel rotates the pointer (the yellow diameter of the circle extended outwards in both directions) traces the discontinuous tangent graph (bright blue) on graph paper.