IIT-JEE 2000Question 351
Let $ABC$ be an equilateral triangle inscribed in the circle $x^{2}+y^{2}=a^{2}$. Suppose perpendiculars from $A,B,C$ to the major axis of the ellipse $\dfrac{x^{2}}{a^{2}}+\dfrac{y^{2}}{b^{2}}=1$, $(a>b)$ meet the ellipse respectively at $P,Q,R$ so that $P,Q,R$ lie on the same side of the major axis as $A,B,C$ respectively. Prove that the normals to the ellipse drawn at the points $P,Q$ and $R$ are concurrent.
Ellipse
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