STEP 1
Equation of parabola : y2 = 8x
On comparing with : y2 = 4ax , 4a = 8 , a = 2
STEP 2 :
P(x , 4) lies on parabola y2 = 8x & hence it must satisfy the equation of the parabola
∴ 42 = 8x
x = 2 , P(2,4)
STEP 3 :
Focal distance of point
P(2,4) = PS
= PM ……….. FOCUS DIRECTRIX PROPERTY
= x + a
= 2 + 2 = 4 units