The maximum distance from the moving point P on the standard ellipse with the focus on the x-axis to the top vertex is equal to the distance from the center of the ellipse to its directrix, and the value range of eccentricity is calculated The maximum distance from the moving point P on the standard ellipse with the focus on the x-axis to the top vertex is equal to the distance from the center of the ellipse to its directrix The upper vertex is (0, b). The range of eccentricity is required!

The maximum distance from the moving point P on the standard ellipse with the focus on the x-axis to the top vertex is equal to the distance from the center of the ellipse to its directrix, and the value range of eccentricity is calculated The maximum distance from the moving point P on the standard ellipse with the focus on the x-axis to the top vertex is equal to the distance from the center of the ellipse to its directrix The upper vertex is (0, b). The range of eccentricity is required!

When p is at the left and right vertices, the distance to the top vertex is the largest, the maximum is √ (a ^ 2 + B ^ 2)
The distance from the center to the guide line is a ^ 2 / C
Then √ (a ^ 2 + B ^ 2) = a ^ 2 / C
That is, a ^ 2 + A ^ 2-C ^ 2 = a ^ 4 / C ^ 2
That is, a ^ 4-2a ^ 2C ^ 2 + C ^ 4 = 0
(a^2-c^2)=0
a^2=c^2
A = C (impossible)
The title is wrong. Does the upper vertex refer to the point (0, b)?