S=1/2 a^2sin60=√3/4a^2当a=1, s=√3/4,当a=√3, s=3√3/4,当a=2, s==√3.
S=(1/2)*a*(√3/2)*a=(√3/4)*a*aa=1,S=(√3/4)a=√3,S=3√3/4a=2,S=√3