Let P(t,t−2,t) and Q(2s−2,s,s)
DR′s of PQ are (2,1,2)
⇒22s−2−t=1s−t+2=2s−t
⇒22s−2−t=1s−t+2
⇒2s−2−t=2s−2t+4
⇒t=6
⇒1s−t+2=2s−t
⇒1s−6+2=2s−6
⇒2s−8=s−6
⇒s=2
⇒P(6,4,6) and Q(2,2,2)
PQ:2x−2=1y−2=2z−2=λ
⇒x=2λ+2,y=λ+2andz=2λ+2
Let, F(2λ+2,λ+2,2λ+2)

A(1,2,12)
AF⋅PQ=0
⇒2(2λ+1)+1(λ)+2(2λ−10)=0
⇒4λ+2+λ+4λ−20=0
⇒λ=2
So F(6,4,6) and AF=65
⇒l2=65