A. 1

B. 2

C. 3

D. 4

From any point on the circle x^{2}+y^{2}=a^{2} tangents are drawn to the circle x^{2}+y^{2}=a^{2} sin^{2}θ. The angle between them is

If the tangent at P on the circle x^{2}+y^{2}=a^{2} 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 x^{2}+y^{2}=3a^{2 }, x^{2}+y^{2}-6x-8y+9=0 touch externally then a=