" 56.If the circles "x^(2)+y^(2)-6x-8y+c=0" and "x^(2)+y^(2)=9" have three common tangents "

If the circles x^(2) +y^(2) - 6x – 8y +c = 0 and x^(2) + y^(2) =9 have three common tangent then c=

If the circleS x^(2)+y^(2)-6 x-8 y+c=0 and x^(2)+y^(2)=9 have three common tangtnts then c=

The circles x^(2) +y^(2) + 2ax +c =0 and x^(2) +y^(2) +2bx +c =0 have no common tangent if

the no.of possible integral values of m for which the circle x^(2)+y^(2)=4 and x^(2)+y^(2)-6x-8y+m^(2)=0 has exactly two common tangents are

The common tangents to the circles x^(2) +y^(2) +2x = 0 and x^(2) +y^(2) -6x= 0 from a triangle which is :

Prove that the circles x^(2)+y^(2)-6x-6y+9=0 and x^(2)+y^(2)+6x+6y+9=0 are such that (A) they do not intersect.(B) their exterior common tangents are parallel (C) their interior common tangents are perpendicular.