a) In triunghiul ABD: AD=30mm ,AB=40 mm =>[tex]BD^{2} = 30^{2} + 40^{2}
[/tex]
[tex] BD^{2} =900+1600[/tex]
[tex]BD= \sqrt{2500} =50mm[/tex]
b) A ABFE(trapez dreptunghic deoarece mB=90,mF=90,EF=AB/2)=(AB+EF)*EM(inaltime,EM perpendiculara pe AB)/2=60*30/2=900[tex]mm^{2} [/tex]