Which one of the following curves cuts the parabola y2=4ax at right angles
y2=4ax⇒2y(dydx)1=4a⇒(dydx)1=2ay ....(i) Taking curve y=e−x2a (dydx)2=e−x2a(−12a)=−y2a ....(ii) Both curves cut orthogonally if, (dydx)1(dydx)2=−1⇒(−y2a)(2ay)=−1