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

Find the angle between the lines joining the points $(0, 0), (2, 3)$ and $(2, -2), (3, 5)$.

If the straight line $2x - 3y + 17 = 0$ is perpendicular to the line passing through the points $(7, 17)$ and $(15, \beta)$,then $\beta$ equals:

If $3x + 4y - 5 = 0$ and $4x + ky - 8 = 0$ are two parallel lines,find the value of $k$.

The angle between the line $x+y=3$ and the line joining the points $(1,1)$ and $(-3,4)$ is

Find the equation of the lines passing through the origin and making an angle of $\tan^{-1} m$ with the line $y = mx + c$.