Questions in circle

Select	Question
	The two circles which passes through $(0,a)$ and $(0,-a)$ and touch the line $y=mx+c$ will intersect each other at right angle, if
	The equation of the tangents to the circle ${{x}^{2}}+{{y}^{2}}+4x-4y+4=0$ which make equal intercepts on the positive coordinate axes is given by
	The angle between the tangents from $(\alpha ,\beta )$ to the circle ${{x}^{2}}+{{y}^{2}}={{a}^{2}}$ , is
	The equation of the tangent to the circle ${{x}^{2}}+{{y}^{2}}-2x-4y-4=0$ which is perpendicular to $3x-4y-1=0$ , is
	The equation of the tangent to the circle ${{x}^{2}}+{{y}^{2}}={{a}^{2}}$ which makes a triangle of area ${{a}^{2}}$ with the co-ordinate axes, is
	If the line $3x-4y=\lambda $ touches the circle ${{x}^{2}}+{{y}^{2}}-4x-8y-5=0$ , then $\lambda $ is equal to
	If a circle passes through the points of intersection of the coordinate axis with the lines $\lambda x-y+1=0$ and $x-2y+3=0$ , then the value of $\lambda $ is
	Tangents drawn from origin to the circle ${{x}^{2}}+{{y}^{2}}-2ax-2by+{{b}^{2}}=0$ are perpendicular to each other, if
	The line $lx+my+n=0$ is normal to the circle ${{x}^{2}}+{{y}^{2}}+2gx+2fy+c=0$ , if
	Given the circles ${{x}^{2}}+{{y}^{2}}-4x-5=0$ and ${{x}^{2}}+{{y}^{2}}+6x-2y+6=0$ . Let P be a point $(\alpha ,\beta )$ such that the tangents from P to both the circles are equal, then