The length of DC can refer to different things depending on the context, such as a measurement in a geometric figure, a distance in geography, or the length of a specific segment in a diagram.
If we are discussing the length of DC in the context of a geometric shape, such as in a triangle, we usually find this length using various formulas depending on the information available, like the coordinates of points or the application of the Pythagorean theorem.
In a geographical context, if you mean the distance from Washington D.C. to another city, that would be specific to the locations involved and can be found using map services or distance calculators online.
To provide a more accurate answer, it would help to clarify the specific context in which you are asking about the length of DC.