a,b,c成等比数列,
b^2=ac
a+c=√3
a^2+c^2+2ac=3
b^2=a^2+c^2-2accos60=a^2+c^2-ac=3-3ac=3-3b^2
4b^2=3
b=√3/2
ac=b^2=3/4,a+c=√3,
x^2-√3x+3/4=0
x=√3/2
a=c=√3/2