Question

Answer 1

Câu 31: Diện tích tam giác ABC là: \(S_{ABC}=\frac12\cdot AB\cdot AC\cdot\sin BAC\)

\(=\frac12\cdot6\cdot4\cdot\sin60=3\cdot4\cdot\frac{\sqrt3}{2}=\frac{12\sqrt3}{2}=6\sqrt3\left(\operatorname{cm}^2\right)\)

=>Chọn D

Câu 30: \(Q=5\sqrt{3x}-\sqrt{12x}+\sqrt{75x}+15\)

\(=5\sqrt{3x}-2\sqrt{3x}+5\sqrt{3x}+15=8\sqrt{3x}+15\)

=>Chọn B