Very simple question, The equation of a Hyperbolic Cylinder is (x2/a2)-(y2/b2)=1, where x2 denotes x^2. here x=0 and y=0 are called principle axes Refer to http://en.wikipedia.org/wiki/Quadric The given equation can be written as, ( x+y-z )^2- (y-z)^2 = 1 Hence the given equation is a Hyperbolic Cylinder with x+y-z=0 and y-z=0 as principle axes.
Satyaram B V,
General Secretary, Mandakini Hostel,
IIT Madras