Răspuns:
[tex]a)[/tex]
[tex]GA'=\frac{1}{2}*GA=5=>GA=10[/tex]
[tex]b)[/tex]
Aria triunghiului ABA' = [tex]\frac{AD*\frac{BC}{2} }{2}=\frac{AD*BC}{4}[/tex]
Aria triunghiului ABC = [tex]\frac{AD*BC}{2}[/tex]
Raportul = [tex]\frac{\frac{AD*BC}{4} }{\frac{AD*BC}{2} } =\frac{1}{2}[/tex]