Are the edges of postcard perpendicular?

Find the perpendicular distance of (1,0,0) from the line (x-1)/(2)=(y+1)/(-3)=(z+10)/(8) Also find the coordinates of foot of perpendicular and the equation of the perpendicular.

Find the equation of the plane passing through the point (3,-3, 1) and perpendicular to the line joining the points (3, 4, - 1) and (2, - 1,5). Also find the coordinates of the foot of the perpendicular, the equation of the perpendicular line and the length of perpendicular drawn from the origin to the plane.

Prove that any two edges in a regular tetrahedron are perpendicular.

In a tetrahedron, if two pairs of opposite edges are perpendicular to each other, prove that the third pair is also perpendicular and that the sum of the squares on the two opposite edges is same for each pair.

The diagonals of a rhombus are perpendicular to each other .

State Theorem of perpendicular axis.