$A$ point is on the $x$-axis. What are its $y$-coordinate and $z$-coordinate?

Let $A, B, C$ be the feet of perpendiculars from a point $P$ on the $x, y, z$-axes respectively. Find the coordinates of $A, B$ and $C$ for the following points $P$:
$(i)$ $(3, 4, 2)$
$(ii)$ $(-5, 3, 7)$
$(iii)$ $(4, -3, -5)$

If $P(5, 4, a)$ and $Q(-1, 2, -2)$ are two points such that $PQ = 7$,then the values of $a$ are ..........

The distance of the point $(a, b, c)$ from the $z$-axis is:

The distance of the point $(4, 3, 5)$ from the $y$-axis is

Find the distance from the origin to the point $(6, 6, 7)$.