Daca AB perpendicular pe BD=> ABD triunghi dreptunghic cu B=90 grade.
BD - cateta=12
AB - cateta=9
AD ipotenuza=?
Facem pitagora
AD^2=12^2+9^2
AD^2=144+81
AD^2=225
AD= radical din 225
AD=15
Paralelogram=> AD=BC=15
DC=AB=9
Perim=9+9+15+15
Perim=18+30
Perim=48
