A Right Angle at the Top Vertex

Problem

In the plane, the ellipse C:x23+y2=1C: \dfrac{x^2}{3} + y^2 = 1 has top vertex AA. A line \ell not through AA meets CC at PP and QQ with APAQ=0\overrightarrow{AP} \cdot \overrightarrow{AQ} = 0.

1. Does \ell pass through a fixed point? Find it or explain why not. 2. The tangents to CC at PP and QQ meet at BB. Find the range of the area of BPQ\triangle BPQ.

Answer

Solution

Difficulty7/10
TopicsPole and Polar, Affine Transformation, conic sections, analytic geometry, Vieta's Formulas

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