Question

Answer 1

Giải thích:

\(S_{ADC}=S_{ABC}=\dfrac{S_{ABCD}}{2}=\dfrac{160}{2}=80\left(cm^2\right)\)

Do N là trung điểm DC \(\Rightarrow S_{ANC}=\dfrac{S_{ADC}}{2}=\dfrac{80}{2}=40\left(cm^2\right)\)

Do M là trung điểm BC \(\Rightarrow S_{AMC}=\dfrac{S_{ABC}}{2}=\dfrac{80}{2}=40\left(cm^2\right)\)

\(S_{AMCN}=S_{AMC} +S_{ANC}=40+40=80\left(cm^2\right)\)

Answer 2

Chọn D