\(\therefore\) Balancing force in vertical direction,
\(N \cos 30^{\circ}-{mg}-\mu {N} \cos 60^{\circ}=0\)
\(\Rightarrow {N}\left[\cos 30^{\circ}-\mu \cos 60^{\circ}\right]={mg}\)
\(\therefore {N}=\frac{800 \times 10}{(0.87-0.1)} \approx 10.2 \times 10^{3} {kgm} / {s}^{2}\)