[tex]D= \sqrt{L^2+l^2+h^2} =12[/tex]
ridicam la patrat si obtinem:
[tex] L^2+l^2+h^2 =144[/tex]
L+l+h=19. ridicam la patrat si obtinem:
[tex]L^2+l^2+h^2+2(Ll+Lh+lh)=361[/tex]
Aria paralelipipedului are formula A=2(Ll+Lh+lh)
Deci 144+A=361
De unde rezulta A=361-144=217 cm patrati.
