Triangle ABC is isosceles triangle, and angle a is 36 degrees Find the value of BC / ab

Triangle ABC is isosceles triangle, and angle a is 36 degrees Find the value of BC / ab

because
Triangle ABC is isosceles triangle, and angle a is 36 degrees
therefore
This triangle is the golden triangle
therefore
BC/AB = (sqrt(5)-1)/2
The bisector angle B can be proved
Triangle ABC is similar to triangle BCD