Răspuns:
Explicație pas cu pas:
Aplicam teorema bisectoarei:
[tex]\frac{BD}{DC} =\frac{AB}{AC} \\\frac{BD}{DC} =\frac{16}{20} =\frac{4}{5}\\BD=\frac{4DC}{5} \\BD + DC = BC = 18\\\frac{4DC}{5} + DC =18\\4DC + 5DC = 90\\9 DC = 90\\DC = 10 cm\\BD = 18 - 10 = 8 cm\\[/tex]