What does it look like when you take the sine of a circle? Not the angle of points on a circle, but the circle itself as a set of points in the complex plane?
Here’s a plot for the sine of circles of radius r centered at the origin, 0 < r < π/2.
Here’s the same plot but for π/2 < r < π.
Now let’s see what happens when we shift the center of the circle over by 1, first for 0 < r < π/2.
And now for π/2 < r < π.
Here’s the Python code that produced the first plot; the code for the other plots is very similar.
import matplotlib.pyplot as plt from numpy import pi, exp, sin, linspace t = linspace(0, 2*pi, 500) for r in linspace(0.1, pi/2, 17): z = r*exp(1j*t) w = sin(z) plt.plot(w.real, w.imag, 'b') plt.gca().set_aspect("equal") plt.title("$\sin(r\exp(it))$, $0 < r < \pi/2$") plt.show()