Let F1F2 be the focus of the hyperbola X / 4 minus y, p be on the hyperbola, and

Let F1F2 be the focus of the hyperbola X / 4 minus y, p be on the hyperbola, and

Hyperbola X / 4 minus y = 1 A ^ 2 = 4 B ^ 2 = 1 C ^ 2 = a ^ 2 + B ^ 2 = 5
Let Pf1 = m, PF2 = n
Hyperbola definition | M-N | = 2A = 4
And