Why are cis and trans isomers of succinic acid impossible?

            Due to the absence of double bond in Succinic Acid.

Explanation:

                  cis-trans Isomerism also known as Geometrical Isomerism is a type of isomerism in which isomers have same molecular formula and structural formula but differ in respect of arrangement of groups or atoms about the double bond.

                 Therefore, a double bond is the main requirement for such isomerism process.

Example:

              cis and trans Butene. In cis-Butene both methyl groups are located on the same side. While, in trans-Butene both methyl groups are in opposite directions (Figure red).

Result:

          As shown in figure, succinic acid (blue) is lacking a double bond. Therefore, it fails to show cis-trans isomerism.

the answer is:  

line graphs show patterns in data with variables that change over time; whereas, circle graphs show data as parts out of a whole (such as out of 100%).