Răspuns:
B
| D
|
A___________C
AD/BD = rad3 =>AD=BDrad3
AB^2 = BD^2 + 3BD^2
AB^2 = 4BD^2
AB=2BD
=>m(<BAD)=30° (reciproca t. <30°)
=>m(<DAC)=90°-30°=60°
=>m(<DCA)=30°
AD cateta opusă unghiului de 30°
=>AD=AC/2=18rad6 cm
18rad6 =BD•rad3 =>BD=18rad6/rad3
BD=18rad2 cm
t.h. : AD^2 = BD•DC
1944=18rad2•DC
DC=108/rad2=54rad2 cm
BC=18rad2+54rad2
BC=72rad2 cm
Aria=(AD•BC)/2=(18rad6•72rad2)/2
=>Aria=1296rad3 cm^2
AB^2 = BC^2 - AC^2
AB^2 = 10368-7776
AB = 36rad2 cm
P=36rad2+36rad6+72rad2
P=36(3rad2+rad6) cm
