O = (0, 0, 0)
A = (0, 0, 4)
B = (0, 0, -4)
a, c, b = Cone(A, O, 3)
d, e, f = Cone(B, O, 3)
g = 2 (slider from -5 to 5, step 0.1)
P = (0, 2, 2)
Q = (2, 0, 2)
R: (-1, 1, g)
h = Plane(P, Q, R)
k = IntersectPath(h, a)
C, D, G, H = Corner(k)
p = IntersectPath(h, d)
E, F, I, J = Corner(p)

Tool: tgpin
Input: A, B, C, D
Output: h

a = Line(C, D)
b = Line(A, B)
E = Intersect(a, b)
F = Midpoint(A, E)
d = Circle(F, A)
f = OrthogonalLine(B, b)
G = Intersect(d, f, 2)
g = Circle(E, G)
H = Intersect(g, a, 2)
h = Circle(A, B, H)