A. 12(x-a)2-4y2=3a2
B. 9(x-a)2-5y2=2a2
C. 8x2-3(y-a)2=9a2
D. none
The equation of the circle belonging to the coaxal system of which (1, 2)(4, 3) are the limiting points and passing through the origin is
The length of the intercept made by the circle x2+y2+10x-12y-13=0 on y-axis is
The angle between a pair-of tangents drawn from a point P to the circle x2+y2+4x-6y+9sin2α+13cos2 α=0 is 2α.The equation of the locus of the point P is
The equation of the circle with centre at (-3, 4) and touching y-axis is
The centre of the circle (1+m2)(x2+y2)-2cx-2cmy=0 is
The equation of the circle which cuts orthogonally the three circles x2+y2+4x+2y+1=0, 2x2+2y2+8x+6y-3=0 , x2+y2+6x-2y-3=0 is
If the lines 3x-4y-7 =0and 2x-3y-5=0 are two diameters of a circle of area 49π sq unit. Then the equation of this circle is
The number of common tangents to the circles x2+y2+2x+8y-23=0, x2+y2-4x-10y+19=0 is
If the lines 2x-3y=5 and 3x-4y=7 are two diameters of a circle of radius 7, then the equation of the circle is
The centre of the circle x2+y2-4x-2y-4=0 is