If the combined equation of the diagonals of the square formed by the pairs of lines $xy+4x-5y-20=0$ and $xy-5x+4y-20=0$ is $x^2-y^2-kx+ly=0$,then $k+l=$.

If the angle between the pair of lines $x^2+2 \sqrt{2} x y+k y^2=0, k>0$ is $45^{\circ}$,then the area (in square units) of the triangle formed by the pair of bisectors of angles between the given lines and the line $x+2 y+1=0$ is

If the lines $x^2-4xy+y^2=0$ and $x+y=10$ contain the sides of an equilateral triangle,then the area of the equilateral triangle is

The area of the triangle formed by the lines represented by $3x + y + 15 = 0$ and $3x^2 + 12xy - 13y^2 = 0$ is

If the lines $ax^2 + 2hxy + by^2 = 0$ represent the adjacent sides of a parallelogram,then the equation of the second diagonal,if one diagonal is $lx + my = 1$,will be

From the point $(3,-4)$,perpendicular lines $L_1$ and $L_2$ are drawn to each of the lines represented by $S \equiv 2x^2+3xy-2y^2-7x+y+3=0$. The area of the quadrilateral formed by the pair of lines $S=0$,$L_1$,and $L_2$ is (in square units):