The diagonals of a parallelogram bisect each other.
That means they have the same midpoint.
See the Math Notes box in Lesson 7.3.3 for help finding the midpoint of the line segment which connects
The midpoint is
Use the eTool below to explore the diagonals of a parallelogram.
Click the link at right for the full version of the eTool: 8-55 HW eTool (Desmos)