Questions in 3-d

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	The ratio in which the sphere ${{x}^{2}}+{{y}^{2}}+{{z}^{2}}=504$ divides the line segment AB joining the points $A\ (12,\ -4,\ 8)$ and $(27,\ -9,\ 18)$ is given by
	If two spheres of radii ${{r}_{1}}$ and ${{r}_{2}}$ cut orthogonally, then the radius of the common circle is
	If the plane $2ax-3ay+4az+6=0$ passes through the midpoint of the line joining the centres of the spheres ${{x}^{2}}+{{y}^{2}}+{{z}^{2}}+6x-8y-2z=13$ and ${{x}^{2}}+{{y}^{2}}+{{z}^{2}}-10x+4y-2z=8$, then $a$ equals
	The plane $x+2y-z=4$ cuts the sphere ${{x}^{2}}+{{y}^{2}}+{{z}^{2}}$ $-x+z-2=0$ in a circle of radius
	The radius of sphere $x+2y+2z=15$ and ${{x}^{2}}+{{y}^{2}}+{{z}^{2}}-2y-4z=11$ is
	The equation of the sphere concentric with the sphere $2{{x}^{2}}+2{{y}^{2}}+2{{z}^{2}}-6x+2y-4z=1$and double its radius is
	If (2, 3, 5) is one end of a diameter of the sphere ${{x}^{2}}+{{y}^{2}}+{{z}^{2}}-6x-12y-2z+20=0$then co-ordinates of the other end of the diameter are