A. 2√7
B. √7
C. 4√7
D. 8√7
If x2+y2-4x+6y+c=0 represents a circle radius 5 then c=
The equation of the circle cutting orthogonally the circles x2+y2-8x-2y+16=0, x2+y2-4x-4y-1=0 and passing through the point (1, 1) is
If x2+y2+2gx+2fy+9=0 represents a circle with centre (1, -3) then radius=
The number of common tangents to the two circles x2+y2-8x+2y=0 and x2+y2-2x-16y+25=0 is
From any point on the circle x2+y2=a2 tangents are drawn to the circle x2+y2=a2 sin2θ. The angle between them is
If the tangent at P on the circle x2+y2=a2 cuts two parallel tangents of the circle at A and B then PA. PB=
If (1,2), (4, 3) are the limiting points of a coaxal system , then the equation of the circle in its conjugate system having minimum area is
If the lines 2x+3y+1=0, 3x+2y-1=0 intersect the coordinate axes in four concyclic points then the equation of the circle passing through these four points is
If the circles x2+y2=3a2 , x2+y2-6x-8y+9=0 touch externally then a=
The equation to the circles whose radius is 3 and which touches internally the circle x2+y2-4x+6y-12=0 at he point (-1, 1) is