Questions in pair-st-lines

Select	Question
	If the angle between the lines represented by the equation ${{y}^{2}}+kxy-{{x}^{2}}$${{\tan }^{2}}A=0$be $2A$, then $k=$
	The angle between the lines $xy=0$ is
	The angle between the lines represented by the equation $4{{x}^{2}}-24xy+11{{y}^{2}}=0$ are
	If the lines represented by the equation $2{{x}^{2}}-3xy+{{y}^{2}}=0$ make angles $\alpha $and $\beta $ with x-axis, then ${{\cot }^{2}}\alpha +{{\cot }^{2}}\beta $=
	Angle between the line joining the origin to the points of intersection of the curves $2{{x}^{2}}+3{{y}^{2}}+10x=0$ and $3{{x}^{2}}+5{{y}^{2}}+16x=0$ is
	The lines ${{(lx+my)}^{2}}-3{{(mx-ly)}^{2}}=0$ and $lx+my+n=0$ form
	The angle between the lines represented by the equation $\lambda {{x}^{2}}+{{(1-\lambda )}^{2}}xy-\lambda {{y}^{2}}=0$, is
	If the sum of the slopes of the lines represented by the equation ${{x}^{2}}-2xy\tan A-{{y}^{2}}=0$be 4, then $\angle A=$
	If $(a+3b)(3a+b)=4{{h}^{2}}$, then the angle between the lines represented by $a{{x}^{2}}+2hxy+b{{y}^{2}}=0$ is
	The angle between the lines represented by the equation $({{x}^{2}}+{{y}^{2}})\sin \theta +2xy=0$ is