Răspuns:
triunghiul ABC-isoscel
BD-h /=> D-mijl AC=> AD=DC=5 cm
in tr ADB: m(<ADB)=90°=> AB^2=AD^2+BD^2
10^2=5^2+BD^2
100=25+BD^2
BD2=100-25
BD^2=75
BD=rad 75
BD=5rad3
b) A=b•h/2
A=BC• BD/2
In tr BDC:m(<BDC)=90°
BC^2=BD^2 +DC^2
BC^2=5rad3^2 +5^2
BC^2=25•3+25
BC^2= 75+25
BC^2=100
BC=10
A=10•5rad3/2
A=5•5rad3
A=25rad3
