Answer:
Explanation:
You can figure out the angle DBC by the alternate interior theorem. Angle DBC=56 degrees. You already figured out BD.
Since we know BD, BC, and the angle DBC we can use the Law of cosine to find CD
The law of cosine is
CD^2=BC^2+BD^2-2(BC)(BD)cos DBC
Plug in what we know
CD^2=18^2+12.1^2-2(18)(12.1)cos 56
CD^2≈228.8387
Find the square root to isolate CD.
CD≈15.1