What do you think? Is the circle a polygon, or not?
As a result of watching a child’s video, I previously wrote a brief piece about the “corners” of a circle. The video was designed to teach children the various shapes—how many sides does a shape have, and how many corners?
The video maintained a circle has no corners. I called that into question. I still do. And yet, I do not. I now think it’s all in how you look at it. Or, you might say, it’s all in the mathematical perspective. Consider.
The Circle by Definition
One can define the two-dimensional circle as the complete collection or “set” of points equidistant from a set point, not part of the circle. In effect, a circle is like a symmetrically exploded point.1 Since it takes at least three points to create a corner, by derivation in this fashion, some say the circle has no corners. But is that the end of the discussion?
Circle a Polygon? By the Method of Limits
One can visualize a circle through the process of incrementally adding sides to a regular polygon. A triangle becomes a square; the square becomes a pentagon; the pentagon becomes a hexagon; the hexagon becomes a heptagon; the heptagon becomes an octagon; and so on.
Overcoming a Contradiction
Even if it could be accomplished, the number of sides would be infinite, rather than zero. There are two ways around this that I can come up with. Option one: it could be declared that a true circle can never be achieved using the method of limits. Therefore, a circle is not a polygon.
However, there is a snag to such a supposition: it suggests the method of limits is not strictly legit for other applications. Yet the concept of limits is the basis for the Calculus. Rather than follow this line of reasoning, perhaps it is better to adopt option two. Ignore the whole issue.
My final take on the matter is that mathematicians need to take stock on reality. Math is only a tool. It, like computers or even words, is not an end in itself, only a tool. To say a polygon of ever increasing sides never makes it to a true circle is short-sighted. A circle is a polygon that has had its number of sides increased over endless time. It made it!
1 If one could say a point is “round”.
Note: You might also enjoy Point on a Line, a Line on a Plane, and a Plane in Space