**non-stretch light rope** $AO$ and $BO$ are attached to a node $O$, $O$ is attached to an object $P$, $BO>AO$, where point $A$ and $B$ are fixed on the same horizontal line. At the beginning, $AO$ is vertical and the two ropes are just stretched. The tensions of $AO$ and $BO$ are denoted as $F_{A}$ and $F_{B}$ respectively. Now, keeping $A$ and $B$ on the same horizontal line, if we **slowly** move point $B$ **to the left**, what can we say about $F_{A}$ and $F_{B}$ as $AB$ increases?

**Note:** Can you rigorously prove it?