Tolong dibantu... No. 2 )

Mapel : Matematika
Kelas : X SMA
Bab : Trigonometri

Pembahasan :
CosA = AB/AC
Cos 30 = 12/AC
√3/2 = 12/AC
√3.AC = 24
AC = 24/√3
AC = 8√3 cm

P = √(AC²- DC²)
P = √((8√3)² - 8²)
P = √(192 - 64)
P = √128
P = √64.2
P = 8√2 cm