Ellipse

for ellipse
SP=ePM
SP^{2}=e^{2}PM^{2}

comparing, focus ≡(1,2)
and equation of directrix = (3x+4y-5)

and e=1/3

now distance of centre from focus is =ae
and distance of centre from directrix is =a/e
there fore distance between focus and directrix is =ae-a/e=distance of(1,2) from directrix

now u have eccentricity an calculate a and then b using b^{2}=a^{2}(1-e^{2})

Thank you
:-)