Ta có: ΔDEF=ΔMNP
\(\Rightarrow\left\{{}\begin{matrix}DF=MP\\EF=NP\end{matrix}\right.\)\(\Rightarrow DF+EF=MP+NP=10\left(cm\right)\)
\(\left\{{}\begin{matrix}MP+NP=10cm\\NP-MP=2cm\end{matrix}\right.\)\(\Rightarrow\left\{{}\begin{matrix}MP=\left(10-2\right):2=4\left(cm\right)\\NP=\left(10+2\right):2=6\left(cm\right)\end{matrix}\right.\)
Vậy \(\left\{{}\begin{matrix}DE=MN=3cm\\DF=MP=4cm\\EF=NP=6cm\end{matrix}\right.\)
Ta có: DEF=MNP (gt)
⇒ DF=MP, DE=MN và EF=NP (*)
⇒ DF+EF=MP+NP
Vì DF+EF=10 (cm) (gt)
⇒ MP+NP=10(cm)
Vì: NP-MP=2 (cm) (gt)
⇒ NP=\(\dfrac{10+2}{2}=6\left(cm\right)\)
⇒ MP=6-2=4 (cm)
Vì DE=MN (c/m trên)
Vì DE=3 (cm) (gt)
⇒ MN=3 cm
Từ (*) ⇒ DF=4 cm, EF= 6cm
ΔDEF=ΔMNP
nên DE=MN; EF=NP; DF=MP
EF+FD=10 nên NP+MP=10
mà NP-MP=2
nên NP=6; MP=4
DE=MN=3cm
NP=EF=6cm
MP=DF=4cm
