prove that the quadrilateral formed by joining the midpoints of the pairs of adjacent sides of a quadrilateral is a parallelogram.
Answers
hello ☺
To prove :-
PS || QR and SR || PQ.
Quadrilateral PQRS is a parallelogram
Proof:-
Draw diagonal BD.As PS is the midsegment of ▲ ABD, we can say that PS || BD.
QR is the midsegment of ▲ BCD,
so QR || BD.
∵ PS || BD and QR || BD
so PS || QR.
SR is the midsegment of ▲ ACD
so now SR || AC.As PQ is the midsegment of ▲ ABC
PQ || AC.∵ SR || AC and PQ || AC by transitivity
SR || PQ.∵ PS || QR and SR || PQ,
∴ quadrilateral PQRS is a parallelogram
hence proved..
thank you
To prove that the quadrilateral formed by joining the midpoints of the pairs of adjacent sides of a quadrilateral is a parallelogram:-
parallelogram is a quadrilateral with both pairs of opposite sides parallel proved by these theorems:-
- (THEOREM: If a quadrilateral has diagonals which bisect each other, then it is a parallelogram).
- (THEOREM: If a quadrilateral has one set of opposite sides which are both congruent and parallel, then it is a parallelogram).
We can use one of these ways in a two-column proof. Bear in mind that, to challenge you, most problems involving parallelograms and proofs will not give you all the information about the presented shape. Here, for example, you are given a quadrilateral and told that its opposite sides are congruent.
We can use one of these ways in a two-column proof. Bear in mind that, to challenge you, most problems involving parallelograms and proofs will not give you all the information about the presented shape. Here, for example, you are given a quadrilateral and told that its opposite sides are congruent.[insert drawing of quadrilateral GOAT with sides GO ≅ TA and TG ≅ OA]
We can use one of these ways in a two-column proof. Bear in mind that, to challenge you, most problems involving parallelograms and proofs will not give you all the information about the presented shape. Here, for example, you are given a quadrilateral and told that its opposite sides are congruent.[insert drawing of quadrilateral GOAT with sides GO ≅ TA and TG ≅ OA]Statement Reason:
- GO ≅ TA and TG ≅ OA (Given)
- Construct segment TO Construct a diagonal
- TO ≅ TO Reflexive Property
- △GOT ≅ △ TOA Side-Side-Side Postulate: If three sides of one △
- are congruent to three sides of another △, then the two △ are congruent
- ∠GTO ≅ ∠ TOA CPCTC: Corresponding parts of congruent △ are
- ∠GOT ≅ ∠ OTA congruent
- GO ∥ TA and TG ∥ OA Converse of the Alternate Interior Angles
Theorem: If a transversal cuts across two lines and the alternate interior angles are congruent, then the lines are parallel
GOAT Definition of a parallelogram: A quadrilateral
with two pairs of opposite sides parallel
The two-column proof proved the quadrilateral is a parallelogram by proving opposite sides were parallel.