AREA

OF
PARALLELOGRAM
ABCD = AREA OF
PARALLELOGRAM
EFCD
 IN

∆ADE AND ∆BCF,
 ANGLE DAE = CBF (CORRESPONDING
ANGLES FROM AD||BC AND
TRANSVERSAL AF)(1)
 ANGLE AED = BFC (CORRESPONDING
ANGLES FROM ED||FC AND
TRANSVERSAL AF)(2)
 THEREFORE,ANGLE ADE = BCF(ANGLE
SUM PROPERTY OF A TRIANGLE)(3)
ALSO, AD=BC(OPPOSITE SIDES OF PARALLELOGRAM
ABCD)(4)
 SO, ∆ADE IS CONGRUENT TO ∆BCF(BY ASA
RULE,USING(1),(3),(4))
 THEREFORE,ar(ADE) = area(BCF)(CONGRUENT FIGURE
HAVE EQUAL AREA)
 NOW, ar(ABCD) = area(ADE) + area(EDCB)
= area(BCF) + area(EDCB)
= area(EFCD)
 SO, PARALLELOGRAMS ABCD AND EFCD ARE EQUAL
IN AREA.
(HENCE PROVED)

THANK YOU
BY-SITIKANTHA MISHRA
R NO -36
IX A

To prove that parallelograms on the same base and between the same parallel lines are equal in area

  • 3.
  • 4.
     IN ∆ADE AND∆BCF,  ANGLE DAE = CBF (CORRESPONDING ANGLES FROM AD||BC AND TRANSVERSAL AF)(1)  ANGLE AED = BFC (CORRESPONDING ANGLES FROM ED||FC AND TRANSVERSAL AF)(2)  THEREFORE,ANGLE ADE = BCF(ANGLE SUM PROPERTY OF A TRIANGLE)(3)
  • 5.
    ALSO, AD=BC(OPPOSITE SIDESOF PARALLELOGRAM ABCD)(4)  SO, ∆ADE IS CONGRUENT TO ∆BCF(BY ASA RULE,USING(1),(3),(4))  THEREFORE,ar(ADE) = area(BCF)(CONGRUENT FIGURE HAVE EQUAL AREA)  NOW, ar(ABCD) = area(ADE) + area(EDCB) = area(BCF) + area(EDCB) = area(EFCD)  SO, PARALLELOGRAMS ABCD AND EFCD ARE EQUAL IN AREA. (HENCE PROVED) 
  • 6.