1) Daca
m(<C) =3/7 m(<D)
Stim ca intr-un paralelogram m(<A)=m(<C) si m(<B)=m(<D)
=> 2*[m(<C)+m(<D)]=360
m(<C)+m(<D)]=180
3/7 m(<D)+ m(<D)=180
3/7 m(<D)+ 7/7m(<D)=180
10/7 m(<D)=180
m(<D)=180*7/10=126°
=> m(<C)=126*3/7=54° =m(<A)
2)CD=AD+24
Perimetru= AB+BC+CD+AD=2*(CD+AD)=168 cm
AD+24+AD=168:2=84
2*AD=60
AD=30 cm