A. a
B. 2a
C. –a
D. a/2
The locus of the centre of circle which touches the line x cos α+y sin α=p and circle (x-a)2+(y-b)2=c2 is
The distance between the limiting points of the coaxial system x2 + y2 – 4x – 2y – 4 + 2λ(3x + 4y + 10)=0
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