(1) When a=b=c, that is, △ABC is an equilateral triangle,

Let a=b=c=x,

The height is (√3/2)x,

Area S=x×(√3/2)x÷2=4√3,

x？ = 16, ∴x=4, which means b=4.

(2) when a < b < c,

a+c=2b .b=(a+c)/2。

By ∠ a+∠ b+∠ c = 180,

2∠B=∠A+∠C= 120 ,∴∠B=60

S=acsinB/2=4√3

ac= 16

Is there a maximum angle twice as large as the minimum angle?