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

If $$\theta_1, \theta_2$$ and $$\theta_3$$ are the angles made by a line with the positive direction of $$X, Y$$ and $$Z$$-axes, then $$\cos 2 \theta_1+\cos 2 \theta_2+\cos 2 \theta_3$$ is equal to

The image of the point $$(2,-3,4)$$ with respect to the plane $$4 x+2 y-4 z+3=0$$, is

If a variable plane cuts the coordinate axes in $$A, B, C$$ and is at constant distance $p$ from the origin, then the locus of the centroid of the tetrahedron $$A B C$$ is equal to