1)P∆=a+b+c, a=b=c
P∆=3a
a=h/sin60°
P∆=3h/sin60°=3*12√3/(√3/2)=36√3*(2/√3)=72
2) d=√3/sin45°=√3*2/√2=2√3/√2
r=d/2=2√3/√2*(1/2)=√3/√2
3) c²=a²+b²-2ab*cos(alfa)
c²=81+576-2*9*24*(√2/2)=441√2≈1247
c≈√1247≈35
Я хз ващее, ну наверное, 135 градусов
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KAD+AKD+KDA=180
KAD=180-AKD-KDA
KAD=180-75-60=45
KAD=KAB
ctgKAB=AB/BK
AB=BK*ctgKAB
AB=5*1=5