If the straight lines `2x+3y-1=0,x+2y-1=0`,and `a x+b y-1=0` form a triangle with the origin as orthocentre, then `(a , b)` is given by (a) `(6,4)` (b) `(-3,3)` (c) `(-8,8)` (d) `(0,7)`

If the straight lines 2x+3y-1=0,x+2y-1=0,and ax+by-1=0 form a triangle with the origin as orthocentre, then (a , b) is given by

The straight lines 3x+y-4=0,x+3y-4=0 and x+y-4=0 form a triangle which is :

The straight lines x + y = 0, 3x + y = 4, x + 3y – 4 = 0 form a triangle which is

Show that the straight line x^2-4xy+y^2=0 and x + y = 3 form an equilateral triangle.

The set of real values of k for which the lines x + 3y +1=0, kx + 2y-2=0 and 2x-y + 3 = 0 form a triangle is

The straight lines x+2y-9=0,3x+5y-5=0 , and a x+b y-1=0 are concurrent, if the straight line 35 x-22 y+1=0 passes through the point (a) (a , b) (b) (b ,a) (c) (-a ,-b) (d) none of these

Show that the straight line x-2y+3=0 and 6x+3y+8=0 are perpendicular .

If the straight lines x+y-2-0,2x-y+1=0 and a x+b y-c=0 are concurrent, then the family of lines 2a x+3b y+c=0(a , b , c) are nonzero) is concurrent at (a) (2,3) (b) (1/2,1/3) (c) (-1/6,-5/9) (d) (2/3,-7/5)

If the lines x - y - 1 = 0, 4x + 3y = k and 2x – 3y +1 = 0 are concurrent, then k is