a) 3, 4, 5 - numere pitagorice => BC = 5 cm
In ΔMAN: m(∡MAN) = 90° => (Teorema lui Pitagora) => [tex]MN^{2} = MA^{2} + AN^{2}[/tex]
AN = AB + BN = 4 cm
AM = 3 cm
3, 4, 5 - numere pitagorice => MN = 5 cm
=> MN = BC = 5 cm
b) In ΔABC si ΔAMN: AB = AM = 3 cm; AC = MN = 4 cm; BC = AN = 5 cm
=> (LLL) => ΔABC ≡ ΔAMN => ∡MNA ≡ ∡BCA
c) ΔABC ≡ ΔAMN => ∡AMN ≡ ∡ABC
