A. common chord of C1 and C2

B. common tangent of C1 and C2

C. radial axis of C1 and C2

D. none

The equation of the circle having centre on the line x+y=1 and touching the lines 3x-4y+2=0, 4x+3y+7= 0 is

The equation of the circle passing through the points (4, 1), (6, 5) and having the centre on line 4x+y-16=0 is

From any point on the circle x^{2}+y^{2}+2gx+2fy+c=0 tangents are drawn to the circle x^{2}+y^{2}+2gx+2fy+c sin^{2}α+(g^{2}+f^{2}) 13cos^{2} α =0

The area of the triangle formed by the positive x-axis and the tangent and the normal at (1, √3) to the circle x^{2}+y^{2}=4 is

The locus of the points from which the lengths of the tangents to the two circles x^{2} + y^{2} + 4x + 3 = 0, x^{2} + y^{2}-6x +5 = 0 are in the ratio 2 : 3 is a circle with centre