Parallelogram Side Length: Finding DC Using Height 12 and Base Segment 5

The problem at hand involves finding the length of side $DC$ using the properties of a parallelogram:

• Step 1: Recognize that in a parallelogram, opposite sides are equal, meaning $AB = DC$ and $AD = BC$.
• Step 2: Analyze the given measurements and diagram. The length labeled as 13 cm does not correspond directly to the parallelogram's sides as vertices are placed differently due to the geometric depiction of parallel lines.
• Step 3: Evaluate the diagram: it's lacking enough information directly connecting the labeled lines to either $AB$, the opposing side length $DC$, or using $AD$ where specified.
• Step 4: Conclusion based on information presented: no direct measure or calculative method allows adherence to standard formulas or express calculation of $DC$ based on what is explicitly visualized and labeled.

Given the insufficient data to deduce the length of $DC$ through standard parallelogram properties, the resolution is that it is indeed impossible to determine $DC$ using provided labels and geometric read from the diagram alone.

Therefore, the correct conclusion is: It is not possible to calculate.