AC^2+(AC+6)^2=900
2AC^2+12AC+36=900
AC^2+6AC-432=0
DELTA=36+1728=1764
AC=(-6+42)/2=18
AB=18+6=24
Aplicam proprietatea bisectoarei
BA/BC=BD/DA
24/30=BD/(AB-BD)
24/30=BD/(24-BD)
4/5=BD/(24-BD)
5BD=96-4BD⇒9BD=96⇒BD=32/3
AD=24-32/3=40/3
Din triunghiulADC-DREPTUNGHIC,CD^2=(40/3)^2+18^2
CD^2=1600/9+324=4516/9