The focus of the ellipse is f1.f2, and there is a point P on the ellipse, so that the angle f1pf2 is equal to 120 degrees, then the value range of eccentricity e of the ellipse is? Answer The focus of the ellipse is f1.f2, and there is a point P on the ellipse, so that the angle f1pf2 is equal to 120 degrees, then the value range of eccentricity e of the ellipse is? The answer is [root 2 / 3.1]

The focus of the ellipse is f1.f2, and there is a point P on the ellipse, so that the angle f1pf2 is equal to 120 degrees, then the value range of eccentricity e of the ellipse is? Answer The focus of the ellipse is f1.f2, and there is a point P on the ellipse, so that the angle f1pf2 is equal to 120 degrees, then the value range of eccentricity e of the ellipse is? The answer is [root 2 / 3.1]

The maximum angle of f1pf2 must be p (0, - b) or (0, b)
If P makes f1pf2 = 120, then: if P (0, - b) or (0, b), f1pf2 > = 120
From trigonometric function: C × tan30 > = B,
Substituting a ^ 2 = B ^ 2 + C ^ 2,
c/a>=sqrt(2)/3