If the lines are perpendicular, then the value of k is

Find the angle between the planes $$x+y+z=1$$​ and $$x-2y+3z=1$$.

​$$\text { The angle between the lines } \frac{x-4}{2}=\frac{y}{1}=\frac{z+1}{-2}, \frac{x-1}{4}=\frac{y+1}{-4}=\frac{z-2}{2} \text { is: }$$​​

​$$\text { Find the angle between the lines } \frac{x-3}{1}=\frac{y-2}{2}=\frac{z+1}{2} \text { and } \frac{x-0}{3}=\frac{y-5}{2}=\frac{z-2}{6} \text {. }$$​​

The angle between the lines $$3x-3y=-2z$$ and $$2x-y = -3z$$​ is:

If the direction ratios of two lines are (1, 2, 3) and (-2, 3, -4), Then the angle between the lines is:

Find the angle between the planes $$x+y+z=1$$​ and $$x-2y+3z=1$$.

​$$\text { The angle between the lines } \frac{x-4}{2}=\frac{y}{1}=\frac{z+1}{-2}, \frac{x-1}{4}=\frac{y+1}{-4}=\frac{z-2}{2} \text { is: }$$​​