Question:Define Parallelogram.
Answer
A parallelogram is a quadrilateral with its opposite sides parallel.
\\begin{graph}
width=200;
line((-2,3),(3,3))
line((3,3),(2,-3))
line((-3,-3),(2,-3))
line((-3,-3),(-2,3))
\\end{graph}Properties(1) Both pairs of opposite sides are equal.(2) A diagonal bisect the area of a parallelogram.(3) Both pairs of opposite angles are equal.(4) The diagonals bisect each other.Theorem: The opposite sides of a parallelogram are equal; the opposite angles are equal; the opposite angles are equal; and a diagonal bisects the parallelogram.Theorem: The diagonals of a parallelogram bisect each other.Theorem: If the opposite sides of a quadrilateral are equal are equal, then the quadrilateral must be a parallelogram.Theorem: If the opposite angles of a quadrilateral are equal are equal, then the quadrilateral must be a parallelogram.Theorem: If the diagonals of a quadrilateral bisect each other,then the quadrilateral must be a parallelogram. Theorem: If one pair of opposite sides of a quadrilateral are equal are parallel, then the other sides must be equal and parallel and the quadrilateral must be a parallelogram.