Răspuns:
Explicație pas cu pas:
a)AD=3DF⇒ DF=AD:3=12:3=4 cm
b)Aaecf=Aabcd
CE²=BC²+BE²=12²+4²=144+16=160 CE=4√10 cm
CF²=CD²+DF²=CE CF=4√10 cm
ΔBEC=ΔDFC Abec=Adfc
Aaecf=Aabcd+Abec-Adcf=Aabcd
Aaecf=12²=144 cm²
AF=AD=DF=12=4=8 cm
Aaecf=16+4√10+4√10+8=24+8√
