Why are all circles similar? (Why is $\pi$ a constant?)
18380
Proof that Pi is constant (the same for all circles), without using limits
128258
Why aren't the graphs of $\sin(\arcsin x)$ and $\arcsin(\sin x)$ the same?
149319
Möbius transformations and concentric circles
2786
The staircase paradox, or why $\pi\ne4$
102730
Is my proof correct? (Conformal equivalence of two circular annuli)
102192
Can someone explain geometric multiplicity?
24730
A circle has the same center as an ellipse and passes through the foci $F_1$ and $F_2$ of the ellipse, two curves intersect in $4$ points.
35464
Why do universal constants have the values they do?
95728
The union of growing circles is not homeomorphic to wedge sum of circles
105423
Why doesn't every integral from 0 to $2\pi$ equal zero?
73253
Question About equal signs in Theorems
49444
Why isn't $e^{2\pi xi}=1$ true for all $x$?
61344
How to relate areas of circle, square, rectangle and triangle if they have same perimeter??
7134
Confusion related to calculation of pi
50038
Proving that $e^\pi=e^{-\pi}$
40837
Why $e^{i(π/3)} \ne -1$?
79983
Finding the exact area of a circle?