Fortune Telling Collection - Zodiac Guide - Let an ellipse E: X2A2+Y2B2 = 1 (A > B > 0), the length of its major axis is twice that of its minor axis, and it is not in the focus. ...
Let an ellipse E: X2A2+Y2B2 = 1 (A > B > 0), the length of its major axis is twice that of its minor axis, and it is not in the focus. ...
Then the coordinates of the intersection of the straight line passing through the focus and perpendicular to the X axis and the ellipse are (c, y0).
Substitute x2a2+y2b2= 1, y0= b2a,
Because the chord length of the straight line passing through the focal point and perpendicular to the X axis is 23,
So 2×b2a=23,
From the meaning of the question, a=2b, substituted in the above formula, a=23, b=6,
So the elliptic equation is X2 12+Y26 = 1.
(2) suppose there is a point M(m, 0) (0 < m < 6) on the straight line of 2,
The straight line is not perpendicular to the x axis,
Let the equation of line L be y = k (x-6) (k ≠ 0).
Let P(x 1, y 1), Q(x2, y2),
(1+2k2) x2-46k2x+12k2-12 = 0 can be obtained from x21y = k (x-6).
Then x 1+x2=46k2 1+2k2, x 1? x2 = 12k 2- 12 1+2k 2。
∴MP=(x 1-m, y 1), MQ=(x2-m, y2), PQ=(x2-x 1, y2-y 1), where x2-x1.
∵ A parallelogram with MP and MQ as adjacent sides is a diamond.
∴(MP+MQ)⊥PQ? (MP+MQ)? PQ=0。
∴(x 1+x2-2m)(x2-x 1)+(y 1+y2)(y2-y 1)=0.
∴x 1+x2-2m+k(y 1+y2)=0.
∴46k2 1+2k2-2m+k2(46k2 1+2k2-26)=0.
Simplified to m = 6k21+2k2 = 61k2+2 (k ≠ 0),
Then m ∈ (0 0,62)
There is a point M(m, 0) and m∈(0, 62) on the straight line of 2.
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