Answer:
choice f
Step-by-step explanation:
take ∆ abc
ab^2 = ac^2 + ab^2
400 = 225 + ab^2
ab =√ 175
∆aDB
bd = 20-x
ad^2 = 175 -(20-x)^2
∆acd
225 = x^2 + 175 - 400+ 40x - x^2
225 = -225 + 40x
450 = 40x
x = 45/4
The mass of the gold bar is = 13.896 kg.
To acheive this answer you have to multiply the area of the trapezium and the length of the bar. Hope this helped x :)