Does every geometric shape have an apothem?

134 Views Asked by At

Does every arbitrary geometric shape have an apothem? This is not entirely clear to me.

(I have heard that the apothem of a geometric shape is a generalization of the notion of the radius of a circle.)

2

There are 2 best solutions below

9
On

An apothem is usually defined for regular polygons, where the idea of "center" is entirely unambiguous. For more irregular shapes, how do we define a center?

Even in cases where the center is clear, it's not hard to construct a polygon that has no segment from the center perpendicular to a side. On the $xy$-plane, join the sequence of points: $(3,0),(1,1),(0,3),(-1,1),(-3,0),(-1,-1),(0,-3),(1,-1),(3,0)$. This is an octagon shaped like a four-pointed star. The origin is its center, but you can't drop a perpendicular from there to any side.

0
On

Apothem is radius of inradius of a polygon. Every polygon can't have a incircle in it.
Therefore every polygon can't have a apothem.