f(x) = If[abs(x) ≤ (2 * π), sin(x)]
a = 6.283185307179586 (slider from (-2 * π) to (2 * π), step 0.1)
A: (a, f(a))
g = Tangent(a, f)
h = Derivative(f)
c = Circle(A, 1)
B, C = Intersect(c, g)
i = Segment(B, C)