Quadrilateral Analysis: Testing Parallelogram Properties with Sides 10, 8 and Diagonals 2, 4

To determine if quadrilateral $ABCD$ is a parallelogram, we apply the condition that a parallelogram has both pairs of opposite sides congruent.

We are given:

• Side $AB = 10$.
• Side $CD = 8$.

To be a parallelogram, not only should $AB = CD$, but $AD$ should be equal to $BC$. However, the provided lengths don't satisfy this condition.

No further information is presented about the length equality of sides $AD$ and $BC$, nor do provided diagonals imply certain conditions towards opposite sides equality.

Since $AB \neq CD$, we immediately conclude the quadrilateral fails to meet the requirement of having both pairs of opposite sides equal as needed for it to be a parallelogram.

Therefore, the quadrilateral $ABCD$ is not a parallelogram.

Conclusion: No