u+v

v-u

A = (0, 0)
B = (5.2, 4.8)
c = Circle(A, B)
u = Vector(A, B)
C = Point(c)
v = Vector(A, C)
α = Angle(C, A, B)
w: u + v
a = Vector(B, C)
D = Point(w)
b = Segment(A, D)
d = Segment(B, C)
E = Intersect(b, d)
β = Angle(B, E, A)