If the normal at the point to the ellipse intersects it again at the point

MATHEMATICS · Subjective · CBSE · Mathematics · Conic Sections · Conic Sections

Problem

If the normal at the point

P(\theta)

to the ellipse

5x^2 + 14y^2 = 70

intersects it again at the point

Q(2\theta)

, show that

\cos \theta = -\frac{2}{3}