Answer:
Square
Step-by-step explanation:
Given


1 and 2 are consecutive
Required
Determine a special name to the parallelogram
For consecutive angles 1 and 2 of a parallelogram, we have:



Collect like terms



Next, is to calculate angles 1 and 2




Both angles are 90.
This implies that each angle in the parallelogram is 90.
<em>Such a parallelogram is either a rectangle or a square</em>