If the straight lines $2x + 3y - 3 = 0$ and $x + ky + 7 = 0$ are perpendicular,then the value of $k$ is:

If $m=1$ is the slope of a line $L$,then the product of the slopes of non-parallel lines which are inclined at an angle of $60^{\circ}$ with $L$ is

To which of the following types do the straight lines represented by $2x + 3y - 7 = 0$ and $2x + 3y - 5 = 0$ belong?

The lines $y = 2x$ and $x = -2y$ are

If the equation of a line having a slope $m$ $(m \in \mathbb{Z})$,passing through $(1, 1)$ and making an angle of $\tan^{-1}\left(\frac{5}{7}\right)$ with the line $x + y - 3 = 0$ is $ax + y + c = 0$,then $ac =$

The angle between the lines $x = 2$ and $x - 3y = 6$ is