Show that the lines `x-7y-22=0, 3x+4y+9=0` and `7x+y-54=0` form a right angled isosceles triangle.

Show that the straight lines x+y=0, 3x+y-4=0 and x+3y-4=0 form an isosceles triangle.

The straight line x+y=0, 3x+y-4=0 and x+3y-4=0 from a triangle which is

Find radical centre of three circles discribed on the three sides 4x-7y+10=0, x+y-5=0 and 7x+4y-15=0 of triangle as diameters .

Find the angle between the lines 2x+y+4=0 and y-3x=7

Find the angle between the lines 2x + y + 4 = 0 and y - 3x = 7

Show that the feet of the perpendicular from (-2,-8) to the lines x-2y+6=0,x-7y+6=0 and x+3y-4=0 are collinear.