cosA=√3/2,a:b=1:√3,
b=√3*a,c=4.
cosA=(b^2+c^2-a^2)/2bc,
√3/2=(3a^2+c^2-a^2)/(2*√3ac)
c^-3ac+2a^2=0,
(c-2a)(c-a)=0,
c=2a,c=a,而,c=4.
a1=2,a2=4.
b1=2√3,b2=4√3.
cosA=√3/2,
A=30度.
a1/sinA=2R,
R1=2,
a2/sin30=2R2
R2=4.
S1圆的面积=∏*R1^2=4∏,
S2圆的面积=∏*R2^2=16∏.
则圆的面积为:4∏,或16∏.