Cho tam giác $ABC$

Đáp án mã đề 124: a) Sai, b) Sai, c) Sai, d) Sai. a) Sai. b) Sai. c) Sai vì $AB=8cm,AC=6cm,\hat{A}=60^0$: $BC=\sqrt{8^2+6^2-\mathrm{2.8.6.}\cos 60^0}=7,2$. d) Sai vì $AB=8cm,AC=6cm,\hat{C}=120^0$: $\frac{AB}{\sin C}=\frac{AC}{\sin B}\Rightarrow \sin B=\frac{AC.\sin C}{AB}=\frac{6.\sin 120}{8}=\frac{3\sqrt{3}}{8}\Rightarrow \hat{B}=40^{0}30^{\prime }$.
a) Sai.
b) Sai.
c) Sai vì $AB=8cm,AC=6cm,\hat{A}=60^0$: $BC=\sqrt{8^2+6^2-\mathrm{2.8.6.}\cos 60^0}=7,2$
d) Sai vì $AB=8cm,AC=6cm,\hat{C}=120^0$: $\frac{AB}{\sin C}=\frac{AC}{\sin B}\Rightarrow \sin B=\frac{AC.\sin C}{AB}=\frac{6.\sin 120}{8}=\frac{3\sqrt{3}}{8}\Rightarrow \hat{B}=40^{0}30^{\prime }$