Given equation of parabola is y2=12x Here, a=3 ∴ Equation of normal is y=mx−2am−am3(∵m=−1) y=−x−2(3)(−1)−3(−1)3 =−x+6+3 ⇒ x+y=9 .......(i) But given normal is x+y=k ∴k=9 Focus of a given parabola is S(3,0). Now, perpendicular distance from S(3,0) to the line (i) is p=