If the equation $ax^{2} + hxy + by^{2} = 0$ represents a pair of coincident lines,then

The equation $r^2 \cos^2 \left(\theta - \frac{\pi}{3}\right) = 2$ represents

What type of triangle is formed by the line $x = a$ and the pair of lines $x^2 - 3y^2 = 0$?

If the equation $7x^2 - 14xy + py^2 - 12x + qy - 4 = 0$ represents a pair of parallel lines,then the value of $\sqrt{p^2 + q^2 - pq}$ is

The equation of the pair of straight lines perpendicular to the pair $ax^2 + 2hxy + by^2 = 0$ is

The combined equation of the straight lines of the form $y=kx+1$ (where $k$ is an integer) such that the point of intersection of each with the line $3x+4y=9$ has an integer as its $x$-coordinate is