Answer: 30.43
Step-by-step explanation: The smaller triangle has an angle of 54°. The hypothenus is 20, so we're looking for the opposite using SOHCAHTOA
Sin x = opp/hyp
Sin 54 =opp/ 20
Opp= sin54 ×20
Opp= 16.18
Therefore, BD is 16.18
In the bigger triangle, with taking the angle 28° we have DC to be the adjacent.
Tan 28° = 16.18/adj
Adj = 16.18/tan 28°
Adj = 30.43
DC = 30.43