A parallelogram is a quadrilateral in which both pairs of opposite sides are parallel. This definition is the basis for proving that a figure is a parallelogram using different statements and reasons.
There are different types of parallelogram, where their properties can be applied to prove their characteristics. Opposite sides are congruent and opposite angles are congruent. Diagonals bisect each other and adjacent angles are supplementary.
There are different ways to prove that a given figure is a parallelogram:
- Show that both pairs of opposite sides are parallel.
- Show that both pairs of opposite sides are congruent.
- Show that both pairs of opposite angles are congruent.
- Show that the diagonals bisect each other.
- Show that one angle is supplementary to both adjacent angles.
- Show that one pair of opposite sides are congruent and parallel.
Given: ZBAC = ZDCA; ZBCA = ZDAC
Prove: ABCD is a parallelogram
Statements:
- <BAC = <DCA; <BCA = <DAC
- BA || DC; BC || DA
- ABCD is a parallelogram
Given: WXYZ; WZ = YX
Prove: WXYZ is a parallelogram
Statements:
- WX ~ UZ; WZ = X
- XZZX
- AWZX ≈ AYXZ
- <WXZ = <YZX; <W ZX =< YXZ
- WX || YZ; WZ || YX
- WXYZ is a parallelogram
Given: PQRS; PQ || RS
Prove: PQRS is a parallelogram
Statements:
- PQ = Rs; P Q || Rs
- <Q PRLS RP
- PR = RP
- AQPR ASRP
- LQRPL SPR
- QR || SP
- PQRS is a parallelogram
Given: JKLM is a parallelogram
Prove: JK = LM and JM = LK
Statements:
- JKLM is a parallelogram
- JK || LM; JM || LK
- AJKL ALMJ
- JK = LM and JM = LK
Given: CDEF is a parallelogram
Prove: ZDCF and ZCFE are supplementary
Statements:
- CDEF is a parallelogram
- CD || EF
- < KJL ≈ LM L J; <MJL ≈ <KW
- JL = LJ
- LDCF and <CFE are supplementary
Given: RSTU is a parallelogram
Prove: ZUZS
Statements:
- RSTU is a parallelogram
- RS || TU
- <SRT = <UTR; <URT=<STR
- RT = TR
- ARUTATSR
- LULS
The definition of a parallelogram is crucial for proving that a given quadrilateral is a parallelogram. Its properties, such as opposite sides and angles being congruent, as well as the diagonals bisecting each other, can be used to demonstrate the characteristics of different types of parallelograms. Through these proofs, it becomes evident that the properties of a parallelogram are sufficient to prove that a quadrilateral is indeed a parallelogram.