The length of the common chord of the circles `x^2 +y^2-2x +4y -20= 0, x^2+ y^2+ 6x+ 10y-2=0` is

The length of common chord of the circles x^2 + y^2 - 6x - 4y + 13 - c^2 = 0 and x^2 + y^2 -4x - 6y + 13 -c^2 = 0 is

The length of the common chord of the circles x^(2) + y^(2) + 2x + 3y + 1= 0 , x^(2) + y^(2) + 4x + 3y + 2 =0 is

The length of the common chord of the circles x^(2) + y^(2) + 2hx + a^(2) = 0 , x^(2) + y^(2) - 2ky - a^(2) = 0 is

The length of the common chord of the two circles x^(2) + y^(2) - 4y = 0 " and " x^(2) + y^(2) - 8x - 4y - 11= 0 is

The length of the common chord of the two circles x^2+y^2-4y=0 and x^2+y^2-8x-4y+11=0 is

The length of the common chord of the two circles x^2+y^2-4y=0 and x^2+y^2-8x-4y+11=0 is