What is parallel gram law ?

# Answer

In mathematics, the simplest form of the **parallelogram law**(also called the **parallelogram identity**) belongs to elementary geometry. It states that the sum of the squares of the lengths of the four sides of a parallelogram equals the sum of the squares of the lengths of the two diagonals. Using the notation in the diagram on the right, the sides are (*AB*), (*BC*), (*CD*), (*DA*). But since in Euclidean geometry a parallelogram necessarily has opposite sides equal

https://en.m.wikipedia.org/wiki/Parallelogram_law