Question

Cho ∆ABC = ∆DEF, biết AB + DE = 10cm; EF = 6cm, AC = 7cm. Tính chu vi ∆ABC

Answer 1

Ta có:

ΔABC=ΔDEF\(\Rightarrow\left\{{}\begin{matrix}AB=DE\\BC=EF\\AC=DF\end{matrix}\right.\)

Mà \(\left\{{}\begin{matrix}AB+DE=10\left(cm\right)\\EF=6\left(cm\right)\\AC=7\left(cm\right)\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}AB=\dfrac{10}{2}=5\left(cm\right)\\BC=6\left(cm\right)\\AC=7\left(cm\right)\end{matrix}\right.\)

Chu vi ΔABC là:

\(C_{ABC}=AB+BC+AC=5+6+7=18\left(cm\right)\)