Răspuns :

Fie ΔABD si ΔCBD
BD - bisectoare
Se aplica teorema bisectoarei
=> AB/BC = AD/DC
6/9 = 4/DC
2/3 = 4/DC
=> DC = 4*3/2
DC = 12/2
DC = 6 cm

PΔABC = AB + BC + AC
AC = AD + DC
AC = 4 + 6
AC = 10 cm

PΔABC = 6 + 9 + 10
=> PΔABC = 25 cm

Spor!