The angle does not matter. Think of it as finding the other side to a triangle. Use

a=39 (line AB)
b=b (the leg we need to find)
c=89 (line BD)


(subtract the 1521 from both sides)

(square root both sides)

b = 80
AD=80
Answer:
The width is 2.
Step-by-step explanation:
The equation is 2 x 3 x ? = 12.
It is 2 long
It is 3 in height
2 x 3 = 6
6 x 2 = 12
so 2 is the width.