Shadowy Man
Contributor
A vertical line is a well-defined geometric figure and there is only one line tangent to the circle at that point. That the mathematical slope is undefined because of the divide by zero is immaterial to my point. You can always rotate the coordinates to a frame in which that tangent has no divide by zero.In calculus we learn that a "corner" on a curve has an undefined tangent--it's not just a case of not being well defined. For example, if we graph the function f(x) = |x|, the curve has a V-shape with a sharp corner at x = 0. The derivative is f'(x) = x/|x|. The slope of the curve at x = 0 is then f'(0) = 0/|0| which is undefined. In other words, the tangent line to the curve at x = 0 is undefined.A corner of a polygon does not have a well-defined tangent
That is correct depending on what you mean by "tangent." The equation of a circle on the Cartesian plane with its center at the origin and radius r is x^2 + y^2 = r^2. The function for the upper-half of this is f(x) = √(r^2 - x^2), and its derivative is f'(x) = -x/√(r^2 - x^2). Note that when x = r, then f'(r) involves division by 0. That means that the derivative and hence the slope of the tangent line at x = r is undefined. The tangent line is vertical....whereas each point on a circle has a well-defined tangent...
Just more obfuscation of the meaning with meaningless pedantry.
Yes, circles don't have corners,...therefore a circle doesn't have corners, like a polygon does.
Thanks for at least admitting that, which was my point back in post 2. You got stuck on the word “on” and here we are a couple hundred posts later finally getting to my point.
Sure. You can. You can draw all kinds of things. But that has nothing to do with whether a circle has corners itself.but like I've already explained, the set of points that make up a circle can include points that are vertices on other curves. In fact, you can trace out an entire circle using vertices on right triangles.
Yes, in the most annoying pedantic way you are correct. I concede I did say “on”. If you did not understand what I meant back in post 2 then you are either utterly blinded by your own pedantry or were jerking me around all these posts for your own entertainment.So it seems that you have the basic concepts about right, but you're not adept at communicating what you mean. To say there are no corner points on a circle is not the same as saying a circle has no corners.