a)
ducem CE _I_AB
sin B=sin 60° =√3/2
CE/BC=CE/12=√3/2 ⇒ CE=12√3/2=6√3 cm CE=AD=6√3 cm
EB=√[12²-(6√3)²]=√(144-108)=√36=6 cm
CE²=AE×EB
(6√3)²=AE × 6
108=AE × 6
AE=108/6=18 cm
DC=AE=18 cm
AB=18+6=24 cm
P=18+24+12+6√3=54+6√3
b)
AC=√[18²+(6√3)²]=√(324+108)=√432=12√3 cm
DB=√[24²+(6√3)²]=√(576+108)=√684=6√19 cm
