theorems (parallelpgram)

Quadrilateral
----Let A,B,C and D be four points on the same plane, if no three of these points are collinear and the segments line segment AB, BC, CD and AD intersect only at their endpoints, then the union of these four segmenst is called a quadrilateral.

Theorem 6-14 PDCT
--> Each diagonal seperates a parallelogram into 2 congruent triangles.

Theorem 6-15 POSC
--> In a parallel, any 2 opposite sides are congruent.

Theorem 6-16 POAC
--> In a parellelogram, any 2 opposite angles are congruent.

Theorem 6-17 PCAS
--> In a parallelogram, any 2 consecutive angles are supplementary.

Theorem 6-18 PDB
--> The diagonals of a parallelogram bisect each other.

Theorem 6-19 DSCP
--> Given a quadrilateral in which both pairs of opposite sides are congruent, then the quadrilateral is a parallelorgram.

Theorem 6-20 SPDC
--> If 2 sides of a quadrilateral are parallel and congruent then the quadrilateral is a parallelogram

Theorem 6-21 DBP
--> If the diagonals of a quadrilateral bisect each other, then a quadrilateral is a parallelogram.

Theorem 6-22 The Middline Theorem
--> The segment between the midpoints of two sides of a triangle is parallel to the 3rd side and is half as long.