Question

Please Help

Answer 1

go to https://www.khanacademy.org/math/geometry/quadrilaterals-and-polygons/quadrilaterals/v/proof-diagonals-of-a-parallelogram-bisect-each-other

Answer 2

here is my reasoning:
let's consider the subsequent drawing:

Answer 3

1) sides AD and BC are congruent, by hypothesis
2) angles DAO and OCB are congruent each other, since they are internal alternate angles of parallel lines AD and CB with transverse line AC
3) similarly, angles ADO, and OBC are congruent each other

Answer 4

So traingles ADO and OBC are congruent each other.
What can you conclude then?