[tex]\displaystyle\bf\\Se~da~\Delta ABC~cu~m(\sphericalangle A)=90^o\\\\\implies~\Delta ABC~este~un~triunghi~dreptungic~in~care:\\\\AB=3~cm~~si~~AC=4~cm~sunt~catete~iar~BC~este~ipotenuza.\\\\Aplicam~teorema~lui~Pitagora.\\\\BC=\sqrt{AB^2+AC^2}=\sqrt{3^2+4^2}=\sqrt{9+16}=\sqrt{25}=5~cm\\\\\boxed{\bf BC=5~cm}[/tex]
