Mathematics

Problem

There are two circles whose equations are

x^2 + y^2 = 9

and

x^2 + y^2 - 8x - 6y + n^2 = 0, n \in I

. If the two circles having exactly two common tangents, then the number of possible values of

n

is a. 2 b. 7 c. 8 d. 9