Let the angle APB=2x and the length of the vector PO be a;

Then the cross product of these two squares = ∣ pa ∣ * ∣ Pb ∣ cos2x = ∣ pa ∣ cos2x = [∣ po ∣ square-1] * [1-2 sinx.

Root 2 of the above formula ≥-3+2

Satisfy if and only if a square =2/a square, that is, 0/4 square of 65438+a =2. . . .

If you don't know, you can keep asking, hehe. . .