If the line $(2x + 3y + 4) + \lambda(6x - y + 12) = 0$ is perpendicular to the line $7x + 5y = 2$,then $\lambda = $

If the coordinates of the vertices $A, B, C$ of the triangle $ABC$ are $(-4, 2)$,$(12, -2)$,and $(8, 6)$ respectively,then $\angle B$ =

The distance of a point $(2, 5)$ from the line $3x + y + 4 = 0$ measured along the lines $L_1$ and $L_2$ are the same. If the slope of line $L_1$ is $\frac{3}{4}$,then the slope of the line $L_2$ is

The angle between the lines $x \cos 30^\circ + y \sin 30^\circ = 3$ and $x \cos 60^\circ + y \sin 60^\circ = 5$ is .....$^\circ$

If $A(-3,3), B(1,1), C(1,-1)$ and $D(-2,-2)$ are the vertices of a quadrilateral,the angle between the diagonals $AC$ and $BD$ is

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