Answer:

Explanation:
Look at the picture.
ΔACD it's a triangle 30° - 60° - 90°. The sides are in ratio 1 : √3 : 2.
Therefore
CD : CB : DB = 1 : √3 : 2.
If BC = 16, then CD = 16 : 2 = 8 and CB = 8√3
ΔABC it's a triangle 45° - 45° - 90°. The sides are in ratio 1 : 1 : √2.
Therefore
AC : AB : CB = 1 : 1 : √2
If CB = 8√3, then AB = x = (8√3)/(√2)
