From the given information, A is a point with co-ordinates (3, -5, 12).

From the figure, we can say that the projection of point A on x-axis will be point H(3,0,0) as the y-coordinate and z-coordinate will be zeros.

Distance between two points is given by

Using this formula,

Distance of point A from x-axis (point H)

=√ 169

=13