It appears that there are two solutions:Let the center of the circle be (h,k). Then the perpendicular distance from the center of the circle to the line to which it is tangent must equal to the radius of the circle. That's the green lines. The perpendicular distance from the point (x1,y1) to the line Ax+By+C=0 is d = Therefore, the perpendicular distance from ine point (h,k) to the line x-3y-11 = 0 is It must equal to the radius so Since (h,k) is on the line x-5y+9=0 x-5y+9=0 h-5k+9=0 h=5k-9 Substitute in That breaks into two equations: 2k - 20 = 10 and -(2k - 20) = 10 2k = 30 and -2k + 20 = 10 k = 15 and -2k = -10 k = 5 h = 5k - 9 h = 5k - 9 h = 5(15) - 9 h = 5(5) - 9 h = 75 - 9 h = 25 - 9 h = 66 h = 16 (h,k) = (66,15) (h,k) = (16,5) The equation of any circle is (x-h)² + (y-k)² = r² The radius r is given as , so r² = 10 So the two circles' equations are: (x-66)² + (y-16)² = 10 and (x-16)² + (y-5)² = 10 Edwin