a parabola, lie like a circle, elipise, and a hyperbola are basic shapes of non euclidian geometery.

they can be expressed as a formula (X= 1 , Y=0)(i have no memory of the formula's and so don't have any idea what that would work out to)on a graph with an X/Y axis.

the basic shapes (listed above) can be 'seen as' what you would get it you took a cone (a solid 3d object) and cut it horizontally (a circle); slightly diagonally (an elipses);
Vertically (parabola): diagonallly at such a sharp angle that the angle of the sides of the cone were increasing faster than the cut, so that you'd never reach the other side! (that is the hardest to visulize!)

(all this is dredge up form elementary school--and mea culpa if i've gotten one wrong..(some younger soul with more recently memory will correct me!))

there is more to geometry, (non euclidian geometery) than these basic shapes.. (but unless prodded,i don't think i will remember them!)

my other obsession