tolong nomer 11 sama 12

11)
AB= 18 cm
<AOB= 30°
<BOC= 90-30= 60°

AB/BC = <AOB/<BOC
18/BC = 30/60
BC= 18*60/30= 18*2= 36 cm


12)
r= 7 cm
@= 45°

busur= 45/360 *2*22/7 *7= 1/8 *44= 5,5 cm