You are probably thinking of the Moebius strip.
a circle ??
square
A figure that has a curved face or curved edge.
A cone perhaps?
semi circle
sphere
A line?
a circle ??
square
cylinder??nope
A figure that has a curved face or curved edge.
A cone perhaps?
semi circle
its a lens...1 curved edge = a circle, 1 flat surface = back, 1 curved surface = front. (these are used in some battery-less flashlights, as an example.)
Curved, the edge is the on the opposite side of the tip.
Knife edge geometry refers to the shape of the cutting edges and the relief behind it. The three main types are Hollow, Taper and Flat..the name refers to the shape of the grinds which makes up the edge geometry.
a cone