(20 13? As shown in the figure, in Rt△ABC, ∠ c = 90, ∠ b = 30, and the side lengths AC and AB are the equations x2-3bx+ about x respectively.

(x-2b)(x-b)=0，

x=2b，x=b，

∫ Side lengths AC and AB are two roots of the equation x2-3bx+2b=0 about X, AC < BC,

∴b>0,AC=b,AB=2b，

From Pythagorean Theorem: BC=3b,

The circumference of ABC is b+2b+3b = (3+3) b.