If the circles `x^2 + y^2 = 9 and x^2 + y^2 + 8 y +C =0` touch each other, then c is equal to

If the circles x^(2)+y^(2)=9 and x^(2)+y^(2)+8y+C=0 touch each other,then c is equal to

If the circles x^2+y^2=9 and x^2+y^2+8y+c=0 touch each other, then c is equal to:

If circles x^(2) + y^(2) = 9 " and " x^(2) + y^(2) + 2ax + 2y + 1 = 0 touch each other , then a =

If the circles x^(2) + y^(2) = a^(2) and x^(2) + y^(2) - 6x - 8y + 9 = 0 touches each other externally, then a = …….

If the circles x^(2) + y^(2) = k and x^(2) + y^(2) + 8x - 6y + 9 = 0 touch externally, then the value of k is

If the circles x^(2) +y^(2) = a and x^(2) + y^(2) - 6x - 8y + 9 = 0 touch externally then a =

Show that the circles x^2 + y^2 - 2y -8x+ 8 = 0 and x^2 + y^2 - 2x + 6y + 6 = 0 touch each other and find the point of contact.

Show that the circles x^2 +y^2 + 2ax + c = 0 and x^2 + y^2 + 2by + c = 0 touch each other if 1//a^2 + 1//b^2 = 1//c.

If the circles x ^2 + y ^2 + 2ax + c = 0 and x ^2 + y ^2 +2by + c = 0 touch each other, prove that 1/a ^2 + 1 b ^2 = 1/c