The equations of the circles are x2+y2−10x−10y+λ=0 and x2+y2−4x−4y+6=0 C1= centre of (1)=(5,5)C2= centre of (2)=(2,2)d= distance between centres =C1C2=9+9=18r1=50−λ,r2=2 For exactly two common tangents we have r1−r2<C1C2<r1+r2⇒50−λ−2<32<50−λ+2⇒50−λ−2<32 or 32<50−λ+2⇒50−λ<42 or 22<50−λ⇒50−λ<32 or 8<50−λ⇒λ>18 or λ<42 Required interval is (18,42)