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QUADRILATERALS. A Study of all things 4 sided. Parallelograms. Definition: A quadrilateral with both pairs of opposite sides parallel. Properties of Parallelograms. Theorems and Conclusions. Theorem # 28 :
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QUADRILATERALS A Study of all things 4 sided
Definition: • A quadrilateral with bothpairs of opposite sides parallel.
Properties of Parallelograms Theorems and Conclusions
Theorem # 28: • If a quadrilateral is a parallelogram, then the pairs of opposite sides are congruent. Parallelograms Both pairs of opposite sides parallel Both pairs of opposite sides congruent.
Theorem # 29: • If a quadrilateral is a parallelogram, then both pairs of opposite angles are congruent. Parallelograms Both pairs of opposite sides parallel Both pairs of opposite sides congruent Both pairs of opposite angles congruent
Theorem # 30: • If a quadrilateral is a parallelogram, then the pairs of consecutive angles are supplementary. Parallelograms Both pairs of opposite sides parallel Both pairs of opposite sides congruent Both pairs of opposite angles congruent Pairs of consecutive angles are supplementary 4 1 2 3
Theorem # 31: • If a quadrilateral is a parallelogram, then the diagonals bisect each other. Parallelograms Both pairs of opposite sides parallel Both pairs of opposite sides congruent Both pairs of opposite angles congruent Pairs of consecutive angles are supplementary Diagonals bisect each other
Example #1: • Name any pairs of parallel sides. • Name any pairs of congruent segments. • Name any pairs of congruent angles. • Name any pairs of supplementary angles. Answers: B C E A D
Parallelogram “HOT FACTS” • 4 Sides – Quadrilateral • 2 pairs of opposite sides parallel • 2 pairs of opposite sides congruent • 2 pairs of opposite angles congruent • 4 pairs of consecutive angles supplementary • Diagonals bisect each other
Proving Quadrilaterals are Parallelograms Are you sure they’re parallelograms?
Theorem # 32: • If a quadrilateral has both pairs of opposite sides congruent, then the quadrilateral is a parallelogram. Parallelograms BOTH pairs of opposite sides congruent parallelogram
Theorem # 33: • If a quadrilateral has both pairs of opposite angles congruent, then the quadrilateral is a parallelogram. Parallelograms BOTH pairs of opposite sides congruent parallelogram BOTH pairs of opposite angles congruent parallelogram
Theorem # 34: • If a quadrilateral has a pair of consecutive angles supplementary, then the quadrilateral is a parallelogram. Parallelograms BOTH pairs of opposite sides congruent parallelogram BOTH pairs of opposite angles congruent parallelogram A pair of consecutive angles supplementary parallelogram 4 1 2 3
Theorem # 35: • If a quadrilateral’s diagonals bisect each other, then the quadrilateral is a parallelogram. Parallelograms BOTH pairs of opposite sides congruent parallelogram BOTH pairs of opposite angles congruent parallelogram A pair of consecutive angles supplementary parallelogram Diagonals bisect each other parallelogram
Theorem # 36: • If a quadrilateral has exactly 1 pair of opposite sides congruent and parallel, then the quadrilateral is a parallelogram. Parallelograms BOTH pairs of opposite sides congruent parallelogram BOTH pairs of opposite angles congruent parallelogram A pair of consecutive angles supplementary parallelogram Diagonals bisect each other parallelogram Exactly 1 pair of opposite sides congruent and parallel parallelogram
Definition: • A quadrilateral with bothpairs of opposite sides parallel. Parallelograms Both pair of opposite sides parallel parallelogram
Area of a Parallelogram • Area = base * height • A = b * h h b
Everything you ever wanted to know about Parallelograms…You now know If you did things right, you should have only used 1 sheet of paper, right?