A Focal Ratio on an Ellipse

Problem

F1,F2F_1, F_2 are the foci of C:x24+y23=1C: \dfrac{x^2}{4} + \dfrac{y^2}{3} = 1. Points A(x1,y1)A(x_1, y_1), B(x2,y2)B(x_2, y_2) on CC satisfy x1+x2=12x_1 + x_2 = \dfrac12 and

AF2=λF2B.\overrightarrow{AF_2} = \lambda\,\overrightarrow{F_2B}.

Find λ\lambda.

Answer

Solution

Difficulty7/10
Topicstrigonometry, Trigonometric Identities, conic sections, Symmetry

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