## Proof That a Ray of Light From One Focus of an Ellipse Passes Through the Other Focus

The ellipse above is such thatis a level curve sois a normal to the ellipse at A so

Henceand the law of reflection is satisfied for rays of light betweenand

The ellipse above is such thatis a level curve sois a normal to the ellipse at A so

Henceand the law of reflection is satisfied for rays of light betweenand