Two Reflection Eccentricities

Problem

1. The ellipse x2a2+y2b2=1\dfrac{x^2}{a^2} + \dfrac{y^2}{b^2} = 1 (with a>b>0a > b > 0) has right focus FF; a line through FF meets the ellipse at A,BA, B, and CC is the reflection of AA across the origin OO. If CFABCF \perp AB and CF=ABCF = AB, find the eccentricity. 2. The hyperbola x2a2y2b2=1\dfrac{x^2}{a^2} - \dfrac{y^2}{b^2} = 1 (a,b>0a, b > 0) has right focus FF; a line through FF meets the hyperbola at A,BA, B, and CC is the reflection of AA across OO. If CFABCF \perp AB and CF=FBCF = FB, find the eccentricity.

Answer

Solution

Difficulty7/10
TopicsReflection, conic sections, analytic geometry, Triangle Geometry, Symmetry

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