A Triangle

a = 6.6 (slider from -5 to 30)
A = (4.9, -0.52)
B = Point(Circle[A, a])
f = Segment(A, B)
c = Circle(A, B)
d = Circle(B, A)
C, D = Intersect(d, c)
g = Segment(A, D)
h = Segment(B, D)
t1, b, d_1, a_1 = Polygon(D, A, B)
α, β, γ = InteriorAngles(t1)