Gir
Author: Pep Bujosa

A = (1, 1)
B = (4, 1)
C = (0, 4)
poly1, c, a, b = Polygon(A, B, C)
Centre = (2, 5)
d = 90 (slider from -180 to 180, step 1)
A' = Rotate(A, d °, Centre)
B' = Rotate(B, d °, Centre)
C' = Rotate(C, d °, Centre)
poly1', c', a', b' = Polygon(A', B', C')
text1: "α = " + d + "°"
e = CircleArc(Centre, C, C')
f = CircleArc(Centre, A, A')
g = CircleArc(Centre, B, B')
C'_1 = Rotate(C, d / 2 °, Centre)
h = CircumcircleArc(C, C'_1, C')
A'_1 = Rotate(A, d / 2 °, Centre)
B'_1 = Rotate(B, d / 2 °, Centre)
k = CircumcircleArc(A, A'_1, A')
p = CircumcircleArc(B, B'_1, B')