Forces and equilibrium — practice question

The diagram depicts a block of mass $10\,\text{kg}$ hanging under a horizontal ceiling from two strings, $AC$ and $BC$, whose lengths are $0.8\,\text{m}$ and $0.6\,\text{m}$ respectively; these strings are fixed to points on the ceiling. The angle $ACB = 90^\circ$. A horizontal force of magnitude $F\,\text{N}$ acts on the block, and the block is in equilibrium.