The value of ' $a$ ' for which the lines $\frac{x-2}{1}=\frac{y-9}{2}=\frac{z-13}{3}$ and $\frac{x-a}{-1}=\frac{y-7}{2}$ $=\frac{z+2}{-3}$ intersect, is

The image of the point $$(2,3,7)$$ in the plane $$2 x+5 y-3 z-19=0$$, is

The distance between the point $$(7,2,4)$$ and the plane determined by the points $$(2,5,-3),(-2,-3,5)$$ and $$(5,3,-3)$$ is

The plane is perpendicular to the planes $$x-y+2 z-4=0$$ and $$2 x-2 y+z=0$$ and passes through $$(1,-2,1)$$ is