The document discusses the properties of a rectangular hyperbola. A rectangular hyperbola is a hyperbola whose asymptotes are perpendicular to each other. The equation of a rectangular hyperbola in standard form is x2/a2 - y2/a2 = 1, where the foci are located at (�a, 0) and the distance between the directrices is 2a. Rotating the hyperbola 45 degrees anticlockwise transforms it into the form x-y=�a2, with the foci now located at (a, a).