ABCD is a isosceles trapezoid with AB=10, DB=8 and angle A=120 degrees what is the length of CD
( This question is not written correctly. Cannot be DB=8 It's either CB=8, or DA=8)
Angle FBC = 120° - 90° = 30°
FC = sin(∠FBC) * 8 = 4
CD = AB + 2 (FC) = 18 units 
