The vector projection of a vector $3\hat i + 4\hat k$ on $Y-$axis is

For the given vector $\vec A =3\hat i -4\hat j+10\hat k$ , the ratio of magnitude of its component on the $x-y$ plane and the component on $z-$ axis is

The magnitude of pairs of displacement vectors are given. Which pair of displacement  vectors cannot be added to give a resultant vector of magnitude $13\, cm$?