a)
AB = 50, BC = 40, CA = 30 } => ΔABC = dreptunghic (Pitagoreic)
Duc CF ⊥ BC
CF = AC·BC/AB = 30·40/50 = 1200/50 = 24 cm
CF = AD => AD = 24 cm
AC² = AF·AB => AF = AC/AB = 900/50 = 18 cm
AF = DC => DC = 18 cm
P = AB + BC + CD + DA = 50 + 40 + 18 + 24 = 172 cm
b)
Duc DF ⊥ AC
DF·AC = AD·DC => DF = AD·DC/AC = 432/30 = 14,4 cm
