You are probably thinking of the Moebius strip.
a circle ??
square
A three-sided shape with one curved side is known as a "curvilinear triangle." This shape consists of two straight sides and one curved side, creating a triangle-like form with a rounded edge. It can be used in various mathematical and design contexts, where a blend of linear and curved geometry is required.
A figure that has a curved face or curved edge.
A cone perhaps?
sphere
a circle ??
square
A line?
A three-sided shape with one curved side is known as a "curvilinear triangle." This shape consists of two straight sides and one curved side, creating a triangle-like form with a rounded edge. It can be used in various mathematical and design contexts, where a blend of linear and curved geometry is required.
A figure that has a curved face or curved edge.
cylinder??nope
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.