Răspuns :
Explicație pas cu pas:
A MAB+ A MDC=ME*AB/2+MB4*DC/2 =1/2(ME*AB+MB4*DC)=1/2(ME*AB+MB4*AB)=1/2*AB*(ME+MB4)=1/2*AB*EB4
dar EB4=DC deci ai 1/2*AB*DC=1/2A ABCD
Răspuns:
Explicație pas cu pas:
MP⊥AB MQ⊥CD
MS⊥AD MR⊥BC
Amab+Amdc=Amad+Ambc=Aabcd/2
MP×AB/2+MQ×QB/2=MS×AD/2+MR×AD/2
AB(MP+MQ)/2=AB×AD/2=Aabcd/2
AD(MS+MR)/2=AD×AB/2=Aabcd/2