Cho tam giac ABC co BC=12cm,gocB=60,goc C=40.Tinh duong cao CH , canh AC VA DIEN TICG TAM GIAC abc
[TEX]\triangle\ BCH[/TEX] vuông tại H
[TEX]\Rightarrow HC=BC.sin60^o=6\sqrt{3}\[/TEX]
[TEX]AC={\frac{HC}{cos10^o}}={\frac{6\sqrt{3}}{cos10^o}}\approx\ 10,55[/TEX]
[TEX]AB=AH+HB=AC.sin10^o+{\frac{BC}{2}}={\frac{6\sqrt{3}}{cos10^o}}.sin10^o+6\approx\ 7,83[/TEX]
[TEX]S_{\triangle\ ABC}={\frac{AB.HC}{2}}\approx\40,70[/TEX]