Question Number 107624 by mnjuly1970 last updated on 11/Aug/20
$$\:\:\:\:\:\:\:{please}\:{prove}: \\ $$$$\:\mathrm{A},\mathrm{B},{C}\:\:{are}\:{angles}\:{of} \\ $$$${triangle}. \\ $$$$\underset{{cylic}} {\sum}\frac{{sinA}+{sinB}}{{cosc}}\geqslant\mathrm{8}{cos}\frac{{A}}{\mathrm{2}}{cos}\frac{{B}}{\mathrm{2}}{cos}\frac{{C}}{\mathrm{2}}\:\:\:\:\:\:\: \\ $$$$ \\ $$