Question

Se considera triunghiul ABC asemenea cu triunghiul DEF.Stiind ca:
a)AB=7 cm,BC=8 cm,CA=10 cm si Perimetrul lui DEF=75 cm,calculati DE,EF,FD
b)DE=7 cm,EF=9 cm,FD=12 cm si Perimetrul lui ABC=70 cm,aflati AB,BC,CA
Repede,va roog!!!

Answer 1

a)AB/DE=AC/DF=BC/EF=(AB+AC+BC)/(DE+DF+EF)
7/DE=10/DF=8/EF=(7+10+8)/75=25/75=1/3
DE=7×3=21
DF=10×3=30
EF=8×3=24

b)DE/AB=DF/AC=EF/BC=(DE+DF+EF)/(AB+AC+BC)
7/AB=12/AC=9/BC=(7+12+9)/70=28/70=2/5
AB=7×5/2=17,5
AC=12×5/2=30
BC=9×5/2=22,5