retta c: ax + by = 0
t(a' b') = M . t(a b)
retta d: a'(x-5) + b'y = 0

a = -0.3 (slider from -5 to 5, step 0.1)
b = 0.7 (slider from -5 to 5, step 0.1)
c: (a * x) + (b * y) = 0
M: {{1, -3}, {-1, 2}}
L1 = NaN
L: (M * (a, b))
d: (x(L) * (x - 5)) + (y(L) * y) = 0
A = Intersect(c, d)
luogo1 = Locus(A, a)
B = (0, 0)
C = (5, 0)