Let point P(asec(theta), btan(theta)) and Q(asec(Phi), btan(phi))
Therefore, the line passes through P and Q:
[y-btan(theta)]/[x-asec(theta)]=[btan(phi)-btan(theta)]/[asec(phi)-asec(theta)]
After that, sub (ae, 0) and (-ae, 0) into the equation, you will get the answer.
Don't forget the...